feat(discover): add http_response_rate to metrics discover dataset

[edwardgou-sentry]

Ports over the http_response_rate to discover metrics dataset

[codecov[bot]]

Codecov Report

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

:white_check_mark: All tests successful. No failed tests found.

Additional details and impacted files

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##           master   #75893       +/-   ##
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- Coverage   90.49%   78.30%   -12.20%     
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  Files        3099     6824     +3725     
  Lines      193934   303825   +109891     
  Branches        0    52271    +52271     
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+ Hits       175504   237899    +62395     
- Misses      18430    59540    +41110     
- Partials        0     6386     +6386