fix(profiling): profiler_id uses underscore

[Zylphrex]

Relay expects this with an underscore instead of a dot.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.74%. Comparing base (6701616) to head (5660e9e).
Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3249      +/-   ##
==========================================
- Coverage   79.33%   78.74%   -0.60%     
==========================================
  Files         132      132              
  Lines       14217    14362     +145     
  Branches     2984     3040      +56     
==========================================
+ Hits        11279    11309      +30     
- Misses       2093     2205     +112     
- Partials      845      848       +3     

Files	Coverage Δ
sentry_sdk/consts.py	90.86% <100.00%> (ø)
sentry_sdk/tracing.py	73.54% <ø> (ø)

... and 4 files with indirect coverage changes