fix(spotlight): Make Django middleware init even more defensive

[BYK]

I just got faced with a situation where even trying to do settings.DEBUG may trigger a Django exception if the settings are not loaded yet, hence widening the capture_internal_exceptions() scope for this.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.93%. Comparing base (6448c70) to head (bce9e47).

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3870      +/-   ##
==========================================
- Coverage   79.93%   79.93%   -0.01%     
==========================================
  Files         137      137              
  Lines       15403    15403              
  Branches     2620     2620              
==========================================
- Hits        12313    12312       -1     
- Misses       2217     2219       +2     
+ Partials      873      872       -1     

Files with missing lines	Coverage Δ
sentry_sdk/spotlight.py	56.36% <100.00%> (ø)

... and 2 files with indirect coverage changes