feat(issue-platform): Add feature flag for issue platform changes

[snigdhas]

Adds a feature flag for the issue platform changes for crons and SD issues.

[codecov]

Codecov Report

Merging #58065 (b146b98) into master (de3a4e8) will increase coverage by 0.66%.
Report is 8 commits behind head on master.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #58065      +/-   ##
==========================================
+ Coverage   78.39%   79.05%   +0.66%     
==========================================
  Files        5135     5135              
  Lines      223461   223464       +3     
  Branches    37624    37625       +1     
==========================================
+ Hits       175185   176666    +1481     
+ Misses      42629    41142    -1487     
- Partials     5647     5656       +9     

Files	Coverage Δ
...dpoints/organization_events_root_cause_analysis.py	96.19% <100.00%> (+0.07%)	⬆️
src/sentry/conf/server.py	89.83% <ø> (ø)
src/sentry/features/__init__.py	100.00% <100.00%> (ø)
static/app/components/avatar/avatarList.tsx	90.90% <ø> (ø)

... and 127 files with indirect coverage changes