feat(devservices): Add metrics mode

[hubertdeng123]

Taken from https://github.com/getsentry/sentry/blob/master/src/sentry/runner/commands/devserver.py#L348-L351

Also, starting events and transactions since that is pretty much always used.

[hubertdeng123]

heard feedback from folks that it is more useful to group spans, metrics, and transactions together for tracing: #93759

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #93766      +/-   ##
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- Coverage   88.03%   84.50%   -3.53%     
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  Files       10329    10329              
  Lines      596109   596109              
  Branches    23146    23146              
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- Hits       524756   503754   -21002     
- Misses      70897    91899   +21002     
  Partials      456      456