[DPE-5312] Update tracing charm libs to retrieve them from tempo coordinator repo

[shayancanonical]

Issue

There are a bunch of tempo tracing related updates:

1. tempo-k8s has been deprecated in favor of tempo ha
2. tracing charm libs need to be fetch-ed from tempo_coordinator_k8s
3. tracing traffic is now relayed through grafana-agent-k8s (like the remaining COS traffic)

Solution

2. update tracing charm libs from new repo
   Test integration with tempo ha + test relay of traffic through grafana-agent-k8s

To be done simultaneously

Update mysql-router-k8s tracing related documentation (in progress)

[paulomach]

lgtm

[taurus-forever]

+6 PRs TODO :-D

Thank you!