x-pack/filebeat/input/internal/httplog: fix reserved-name Windows tests (#49028)

Remove TestMkdirAllReservedNames, which is redundant and fails on
Windows 11/Server 2025 where reserved device names are no longer
restricted.

Update TestEvalSymlinksReservedNames to probe OS behavior by
attempting os.MkdirAll with the reserved name before testing
EvalSymlinks. If directory creation succeeds the OS allows
reserved names and the subtest returns early; otherwise the
existing assertions run unchanged.

Author: efd6

x-pack/filebeat/input/internal/httplog/roundtripper_windows_test.go

@@ -11,7 +11,6 @@ import (
 	"io/fs"
 	"os"
 	"path/filepath"
-	"slices"
 	"testing"
 
 	"golang.org/x/sys/windows"
@@ -46,6 +45,9 @@ func TestEvalSymlinksReservedNames(t *testing.T) {
 	for _, name := range []string{"CON", "PRN", "AUX"} {
 		t.Run(name, func(t *testing.T) {
 			p := filepath.Join(base, name, "somefile.log")
+			if err := os.MkdirAll(filepath.Dir(p), 0o750); err == nil {
+				return
+			}
 			_, err := filepath.EvalSymlinks(p)
 			if err == nil {
 				t.Fatal("expected error from EvalSymlinks, got nil")
@@ -60,30 +62,6 @@ func TestEvalSymlinksReservedNames(t *testing.T) {
 	}
 }
 
-func TestMkdirAllReservedNames(t *testing.T) {
-	base := t.TempDir()
-	tests := []struct {
-		name    string
-		wantErr []error
-	}{
-		{"CON", []error{fs.ErrNotExist}},
-		{"PRN", []error{windows.ERROR_DIRECTORY, windows.ERROR_PATH_NOT_FOUND}},
-		{"AUX", []error{windows.ERROR_DIRECTORY, windows.ERROR_PATH_NOT_FOUND}},
-	}
-	for _, test := range tests {
-		t.Run(test.name, func(t *testing.T) {
-			p := filepath.Join(base, test.name, "logsdir")
-			err := os.MkdirAll(p, 0o750)
-			if err == nil {
-				t.Fatal("expected error from MkdirAll, got nil")
-			}
-			if !slices.ContainsFunc(test.wantErr, func(e error) bool { return errors.Is(err, e) }) {
-				t.Fatalf("MkdirAll(%q) err = %v; want in %v", p, err, test.wantErr)
-			}
-		})
-	}
-}
-
 func TestResolveSymlinksWindowsGlob(t *testing.T) {
 	base := t.TempDir()
 	resolved, err := filepath.EvalSymlinks(base)