Enable Tempo metrics generator

[sevein]

This pull request installs Prometheus in the development environment so we can start capturing application metrics (as opposed to logs or traces). It also enables the metrics generator in Grafana Tempo, which is a mechanism that derives metrics from ingested traces and store them in Prometheus. These metrics are useful in a couple of main ways: span metrics and service graphs.

The Prometheus datasource in Grafana has been configured with exemplars enabled, so you should be able to associate trace data with metric data, something that we can start exploring further once we start producing application metrics.

I've updated the dashboard with a simple service view panel:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.44%. Comparing base (ea92327) to head (99b7eb5).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1047      +/-   ##
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- Coverage   54.47%   54.44%   -0.03%     
==========================================
  Files         103      103              
  Lines        7510     7510              
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- Hits         4091     4089       -2     
- Misses       3169     3170       +1     
- Partials      250      251       +1     

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[jraddaoui]

Really nice, thanks @sevein!