fix(query): sort api_v3 GetDependencies links by parent then child

[samuel7james]

Which problem is this PR solving?

• Resolves [Bug]: api_v3 GetDependencies returns dependency links in nondeterministic order #9126

Description of the changes

• QueryService.GetDependencies builds its result from a Go map, so apiv3.Handler.GetDependencies (the gRPC api_v3 path) returned the same set of dependency links in a different order on repeated identical calls.
• The legacy HTTP handler was already fixed the same way in fix(dep): fix nondeterministic dependency ordering #9119, and the MCP get_service_dependencies tool in [jaegermcp] Add get_service_dependencies tool #8403. This closes the third path the issue calls out as still unsorted.
• Sorts by Parent then Child with slices.SortFunc/cmp.Compare, the same comparator shape fix(dep): fix nondeterministic dependency ordering #9119 used for the legacy handler.

How was this change tested?

• Added TestGetDependencies_SortedByParentThenChild, which feeds the mock storage layer three links in an order that isn't recoverable by insertion order or by CallCount, so it only passes if the handler actually sorts.
• Confirmed the new test fails without the fix (reverted the source change locally, re-ran — it failed with the expected mismatch) and passes with it.
• go test ./cmd/jaeger/internal/extension/jaegerquery/internal/apiv3/... — all pass, including the pre-existing TestGetDependencies, TestGetDependenciesStorageError, and TestHTTPGateway snapshot tests in that package.
• golangci-lint run ./cmd/jaeger/internal/extension/jaegerquery/internal/apiv3/... — 0 issues.
• gofmt -l and go vet on both changed files — clean.
• I ran these scoped to the changed package rather than the full make lint test, since the change itself only touches this one file pair.

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/main/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully: make lint test

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• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[github-actions]

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[Copilot]

🟢 Approval recommended

The focused implementation matches the issue requirements and includes effective regression coverage.

Pull request overview

Ensures deterministic api_v3 dependency responses by sorting links by parent, then child.

Changes:

• Adds canonical dependency sorting.
• Adds regression coverage for unsorted storage results.

File summaries

File	Description
grpc_handler.go	Sorts dependency links before response conversion.
grpc_handler_test.go	Verifies parent/child ordering.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

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[yurishkuro]

there is already an identical earlier PR #9127

[samuel7james]

Closing — you're right, this duplicates #9127, which was already open. Apologies for not checking for an existing PR before starting. #9127 also has your architectural feedback to work from (sorting belongs in QueryService, not duplicated per-transport), which is the better place to continue this fix.