ref: Clean up get_active_propagation_context

[sl0thentr0py]

Description

No longer returns None since the last isolation_scope branch will always have one setup by the constructor.

Issues

• resolves: Clean up PropagationContext None checks #5216
• resolves: PY-2011

[linear]

PY-2011 Clean up PropagationContext None checks

[codecov]

Codecov Report

❌ Patch coverage is 84.61538% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.25%. Comparing base (1ac88a0) to head (516088e).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/scope.py	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@                        Coverage Diff                         @@
##           neel/more-prop-context-cleanup    #5217      +/-   ##
==================================================================
+ Coverage                           84.23%   84.25%   +0.01%     
==================================================================
  Files                                 181      181              
  Lines                               18458    18446      -12     
  Branches                             3282     3276       -6     
==================================================================
- Hits                                15549    15542       -7     
+ Misses                               1902     1900       -2     
+ Partials                             1007     1004       -3     

Files with missing lines	Coverage Δ
sentry_sdk/scope.py	89.12% <84.61%> (+1.05%)	⬆️

... and 2 files with indirect coverage changes