Don't fail if there is no _context_manager_state

[sentrivana]

Root cause fix to follow once we figure it out. This PR just makes the SDK not boom.

If we manage to fix the root cause before the next release, this PR is not necessary.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.88%. Comparing base (4456351) to head (75ce6a7).
⚠️ Report is 3 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4698   +/-   ##
=======================================
  Coverage   84.88%   84.88%           
=======================================
  Files         156      156           
  Lines       16115    16116    +1     
  Branches     2741     2741           
=======================================
+ Hits        13679    13680    +1     
  Misses       1650     1650           
  Partials      786      786           

Files with missing lines	Coverage Δ
sentry_sdk/profiler/transaction_profiler.py	87.76% <100.00%> (+0.33%)	⬆️

... and 1 file with indirect coverage changes