feat(metrics_extraction): user_misery to fall back to Discover

[armenzg]

Unfortunately, the count unique field we have been using is user.id which does not match what Discover uses, thus, the data return diverges.

We need to do some work on Relay in order to have the same user field available to on-demand. Until then we will be dropping support for user_misery in on-demand.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5486d69) 81.42% compared to head (13db3e7) 81.42%.
Report is 13 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #65232      +/-   ##
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- Coverage   81.42%   81.42%   -0.01%     
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  Files        5254     5254              
  Lines      232170   232136      -34     
  Branches    45525    45517       -8     
==========================================
- Hits       189055   189024      -31     
+ Misses      37246    37240       -6     
- Partials     5869     5872       +3     

Files	Coverage Δ
src/sentry/models/project.py	95.75% <ø> (ø)
src/sentry/snuba/metrics/extraction.py	90.90% <ø> (-0.73%)	⬇️
...nents/modals/widgetBuilder/addToDashboardModal.tsx	82.60% <ø> (+1.35%)	⬆️
static/app/components/modals/widgetViewerModal.tsx	77.31% <ø> (ø)
...modals/widgetViewerModal/widgetViewerTableCell.tsx	75.36% <ø> (ø)
static/app/components/replays/replayContext.tsx	54.87% <ø> (+4.35%)	⬆️
static/app/constants/index.tsx	94.44% <ø> (ø)
static/app/views/dashboards/dashboard.tsx	70.94% <ø> (+0.55%)	⬆️
static/app/views/dashboards/datasetConfig/base.tsx	93.33% <ø> (-0.79%)	⬇️
static/app/views/dashboards/detail.tsx	56.65% <ø> (+0.06%)	⬆️
... and 16 more

... and 7 files with indirect coverage changes