Merge branch 'drosse/instrument-observability-ff' into 'master'

Add metric to check how many groups have enabled observability features ff

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/159930



Merged-by: Laura Montemayor <lmontemayor@gitlab.com>
Approved-by: Michał Wielich <mwielich@gitlab.com>
Approved-by: Laura Montemayor <lmontemayor@gitlab.com>
Reviewed-by: Michał Wielich <mwielich@gitlab.com>
Reviewed-by: Ankit Panchal <apanchal@gitlab.com>
Co-authored-by: Daniele Rossetti <drossetti@gitlab.com>