Cleanup test resources to quiet logs

[jack-berg]

Recent changes introduced tests and forgot to shut them down after, which causes really noisy build logs.

Fixing that up, and making it easier to do the right thing by having the TelemetryExporter test interface extend AutoCloseable.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.79%. Comparing base (a756317) to head (783fa7a).
Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #7387   +/-   ##
=========================================
  Coverage     89.79%   89.79%           
  Complexity     6969     6969           
=========================================
  Files           795      795           
  Lines         21122    21122           
  Branches       2056     2056           
=========================================
  Hits          18967    18967           
  Misses         1495     1495           
  Partials        660      660           

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