perf(spans): Use bf index on tag keys

[Zylphrex]

The spans table has a bloom filter index on the tag keys. Make sure to add the right condition to make sure the index is applied.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.01%. Comparing base (88ac464) to head (bd63794).
Report is 6 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #73471   +/-   ##
=======================================
  Coverage   78.01%   78.01%           
=======================================
  Files        6634     6634           
  Lines      296733   296754   +21     
  Branches    51108    51110    +2     
=======================================
+ Hits       231490   231515   +25     
  Misses      58855    58855           
+ Partials     6388     6384    -4     

Files	Coverage Δ
src/sentry/search/events/builder/base.py	91.84% <100.00%> (+0.04%)	⬆️
src/sentry/search/events/datasets/base.py	87.80% <100.00%> (+0.30%)	⬆️
src/sentry/search/events/datasets/spans_indexed.py	88.57% <100.00%> (+0.16%)	⬆️

... and 10 files with indirect coverage changes