feat(relay): Move histogram outliers to global config

[jjbayer]

Histogram outliers are a static piece of metrics extraction config that can be moved to global config. This will reduce network traffic, project config sizes in redis and first and foremost relay in-memory caches.

This PR also fixes a long-standing bug in the outlier config.

ref: https://github.com/getsentry/team-ingest/issues/331

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 77.86%. Comparing base (f535fed) to head (f8a70e8).

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #71004   +/-   ##
=======================================
  Coverage   77.85%   77.86%           
=======================================
  Files        6533     6532    -1     
  Lines      291110   291110           
  Branches    50377    50372    -5     
=======================================
+ Hits       226657   226660    +3     
+ Misses      58218    58211    -7     
- Partials     6235     6239    +4     

Files	Coverage Δ
src/sentry/relay/config/__init__.py	91.94% <100.00%> (ø)
src/sentry/relay/config/metric_extraction.py	90.48% <100.00%> (+0.20%)	:arrow_up:
src/sentry/relay/globalconfig.py	96.55% <100.00%> (+0.25%)	:arrow_up:
src/sentry/snuba/metrics/extraction.py	90.84% <100.00%> (+0.03%)	:arrow_up:

... and 16 files with indirect coverage changes