chore(tracing): Add service to service/metrics catalogs

As warranted by gitlab-org/opstrace/opstrace#2258 (closed), this commit introduces one of our services in groupobservability - tracing to our tool-chain with necessary definitions for service & metrics catalog. Further details to be added in following MRs to keep the scope focused per merge.

Considering how setup our services in groupobservability, the definitions here are roughly replicated from the work that was done previously for Error Tracking within gitlab-org/opstrace/opstrace#2304 (closed).

Link to dashboard snapshot: https://dashboards.gitlab.net/dashboard/snapshot/fSKryVU7aYDqQE1Ubr5vAOzRohDbc8ov?orgId=1.