test: disallow starting continuous profiler if SDK is closed

[armcknight]

It already worked that way, but we didn't have a test explicitly for it.

#skip-changelog

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.517%. Comparing base (c964075) to head (2072277).

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #4961       +/-   ##
=============================================
+ Coverage   92.470%   92.517%   +0.047%     
=============================================
  Files          666       666               
  Lines        78926     78960       +34     
  Branches     28572     28606       +34     
=============================================
+ Hits         72983     73052       +69     
+ Misses        5845      5811       -34     
+ Partials        98        97        -1     

Files with missing lines	Coverage Δ
Tests/SentryTests/SentrySDKTests.swift	97.078% <100.000%> (+0.087%)	⬆️

... and 18 files with indirect coverage changes

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[philprime]

LGTM but tests are failing, probably requires compiler flags for checking if startProfiler is available