Usage ping for test report widget [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

Related to #235524 (closed)

Add a tracking event that fires when people expand the test report summary merge request widget.

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• [-] Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done