telemetry(amazonq): numberOfTestsGenerated correctly emits as 0

[chungjac]

Problem

• NumOfUnitTestCasesGenerated shows non 0 value when LinesOfCodeGenerated and CharsOfCodeGenerated are 0
• Occurs only when ExportResultArchive API did not have any generated code or when the job fails

Solution

• Reset NumOfUnitTestCasesGenerated to 0 when one of these cases occur

---

• Treat all work as PUBLIC. Private feature/x branches will not be squash-merged at release time.
• Your code changes must meet the guidelines in CONTRIBUTING.md.
• License: I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

• This pull request modifies code in src/* but no tests were added/updated.
  • Confirm whether tests should be added or ensure the PR description explains why tests are not required.