Enhance crash telemetry with richer diagnostics and EndBuild hang detection (#13304)

## Summary

When MSBuild crashes via throw-helpers like
`ErrorUtilities.ThrowInternalError`, crash telemetry previously captured
only the throw-helper frame in `StackTop` — making triage nearly
impossible since all `InternalErrorException` crashes look identical.
Additionally, when `EndBuild()` hangs waiting for submissions or nodes,
no telemetry was emitted at all because the crash telemetry in the
`finally` block is unreachable during a hang.

This PR addresses both problems.

## Changes

### Richer crash diagnostics (all crash types)

| Property | Purpose |
|----------|---------|
| `StackCaller` | First meaningful caller frame, skipping known
throw-helpers (`ThrowInternalError`, `VerifyThrow`, etc.) — the frame
you actually need for triage |
| `FullStackTrace` | Complete stack trace with file paths sanitized,
capped at 4096 chars |
| `ExceptionMessage` | Truncated exception message (256 chars) with file
paths redacted to avoid PII |
| `CrashThreadName` | Thread name at crash time (main, worker, node
communication, etc.) |

### EndBuild hang detection

Replaces infinite `WaitOne()` calls in `EndBuild()` with **timed
30-second loops** that emit periodic diagnostic telemetry via
`CrashExitType.EndBuildHang`:

| Property | Purpose |
|----------|---------|
| `EndBuildWaitPhase` | Which wait point is stuck
("WaitingForSubmissions" / "WaitingForNodes") |
| `EndBuildWaitDurationMs` | How long the hang has lasted |
| `PendingSubmissionCount` | Submissions still in the pending dictionary
|
| `SubmissionsWithResultNoLogging` | Submissions that have a result but
`LoggingCompleted` is false — the ones blocking EndBuild |
| `ThreadExceptionRecorded` | Whether a thread exception exists on the
BuildManager |
| `UnmatchedProjectStartedCount` | Orphaned ProjectStarted events (no
corresponding ProjectFinished) |

Hang state is also persisted to `%TEMP%\MSBuild_pid-{pid}.hang.txt` via
`DumpHangDiagnosticsToFile` for later retrieval from customer machines.

### PII protection
All new telemetry properties are sanitized to prevent PII leaks:
- **Stack frames**: File paths replaced with `<redacted>` (preserves
line numbers)
- **Exception messages**: Regex redaction of Windows (`C:\...`) and Unix
(`/...`) paths → `<path>`
- **MSB0001 prefix stripping**: Removes boilerplate `MSB0001: Internal
MSBuild Error:` prefix

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: YuliiaKovalova

src/Build/BackEnd/BuildManager/BuildManager.cs

@@ -1038,9 +1038,22 @@ public void EndBuild()
                     }
                 }
 
-                _noActiveSubmissionsEvent!.WaitOne();
+                {
+                    Stopwatch hangWatch = Stopwatch.StartNew();
+                    while (!_noActiveSubmissionsEvent!.WaitOne(CrashTelemetryRecorder.EndBuildHangDiagnosticsIntervalMs))
+                    {
+                        EmitEndBuildHangDiagnostics("WaitingForSubmissions", hangWatch);
+                    }
+                }
+
                 ShutdownConnectedNodes(false /* normal termination */);
-                _noNodesActiveEvent!.WaitOne();
+                {
+                    Stopwatch hangWatch = Stopwatch.StartNew();
+                    while (!_noNodesActiveEvent!.WaitOne(CrashTelemetryRecorder.EndBuildHangDiagnosticsIntervalMs))
+                    {
+                        EmitEndBuildHangDiagnostics("WaitingForNodes", hangWatch);
+                    }
+                }
 
                 // Wait for all of the actions in the work queue to drain.
                 // _workQueue.Completion.Wait() could throw here if there was an unhandled exception in the work queue,
@@ -1230,6 +1243,53 @@ private void RecordCrashTelemetry(Exception exception, bool isUnhandled)
                 host);
         }
 
+        /// <summary>
+        /// Extracts build state under lock and delegates to <see cref="CrashTelemetryRecorder"/>
+        /// for EndBuild hang diagnostic telemetry emission. Also writes diagnostics to disk
+        /// via <see cref="ExceptionHandling.DumpHangDiagnosticsToFile"/>.
+        /// </summary>
+        private void EmitEndBuildHangDiagnostics(string waitPhase, Stopwatch hangWatch)
+        {
+            int pendingSubmissionCount;
+            int submissionsWithResultNoLogging = 0;
+            bool threadExceptionRecorded;
+            int unmatchedProjectStartedCount;
+            string? host;
+
+            lock (_syncLock)
+            {
+                foreach (BuildSubmissionBase submission in _buildSubmissions.Values)
+                {
+                    if (submission.BuildResultBase is not null && !submission.LoggingCompleted)
+                    {
+                        submissionsWithResultNoLogging++;
+                    }
+                }
+
+                pendingSubmissionCount = _buildSubmissions.Count;
+                threadExceptionRecorded = _threadException is not null;
+                unmatchedProjectStartedCount = _projectStartedEvents.Count;
+                host = _buildTelemetry?.BuildEngineHost ?? BuildEnvironmentState.GetHostName();
+            }
+
+            string diagnostics = $"Phase={waitPhase}, Duration={hangWatch.ElapsedMilliseconds}ms, " +
+                $"PendingSubmissions={pendingSubmissionCount}, WithResultNoLogging={submissionsWithResultNoLogging}, " +
+                $"ThreadException={threadExceptionRecorded}, UnmatchedProjectStarted={unmatchedProjectStartedCount}";
+
+            ExceptionHandling.DumpHangDiagnosticsToFile(diagnostics);
+
+            CrashTelemetryRecorder.CollectAndEmitEndBuildHangDiagnostics(
+                waitPhase,
+                hangWatch.ElapsedMilliseconds,
+                pendingSubmissionCount,
+                submissionsWithResultNoLogging,
+                threadExceptionRecorded,
+                unmatchedProjectStartedCount,
+                ProjectCollection.Version?.ToString(),
+                NativeMethodsShared.FrameworkName,
+                host);
+        }
+
 
         /// <summary>
         /// Convenience method.  Submits a lone build request and blocks until results are available.