unreliable test: graceful shutdown no metric emitted

## Test Details

- Name of test: graceful shutdown no metric emitted
- OS of failure: Linux (Integ)
- VSCode version of failure (minimum/insider/stable): stable
- Link to failing run: https://github.com/aws/aws-toolkit-vscode/commit/8b02b85f05063063d364d6921338a09c7c097556
- Link to failing test: https://github.com/aws/aws-toolkit-vscode/blob/8b02b85f05063063d364d6921338a09c7c097556/packages/core/src/test/shared/crashMonitoring.test.ts#L95-L109

## Log of Test Failure
```
AssertionError [ERR_ASSERTION]: Expected no metrics for "session_end", but some exist
at assertTelemetry (/codebuild/output/src890725234/src/github.com/aws/aws-toolkit-vscode/packages/core/src/test/testUtil.ts:336:16)
at Context. (/codebuild/output/src890725234/src/github.com/aws/aws-toolkit-vscode/packages/core/src/test/shared/crashMonitoring.test.ts:108:24)
```

## Additional Information

Start with packages/core/src/test/shared/crashMonitoring.test.ts lines 95-109 and the failing run linked in the issue. Read assertTelemetry in packages/core/src/test/testUtil.ts around line 336, then reproduce the graceful-shutdown test on Linux. Done means the test reliably confirms that no session_end metrics are emitted.

Written by the indexing model from the issue text.