Add logging relation katib-controller

[rgildein]

Added logging relation and cos integration tests from chisme.

fixes: #187

How I tested it:

from terminal

$ tox -e integration -- --keep-models
$ juju switch test-charm-b81i  # change to test model 
$ juju consume u1-k8s:cos.loki-logging
$ juju integrate loki-logging grafana-agent-k8s
$ juju config katib-controller custom_images='{"default_trial_template": "custom:1.0", "early_stopping__medianstop": "custom:2.1"}'  # revert changes from test_blocked_on_invalid_config test
$ kubectl logs -n test-charm-b81i katib-controller-0 --container katib-controller --tail 100 | grep '\[katib-controller\]'
2024-06-17T13:36:27.023Z [katib-controller] {"level":"info","ts":"2024-06-17T13:36:27Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:36:27.026Z [katib-controller] {"level":"info","ts":"2024-06-17T13:36:27Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:36:35.243Z [katib-controller] {"level":"info","ts":"2024-06-17T13:36:35Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:36:35.246Z [katib-controller] {"level":"info","ts":"2024-06-17T13:36:35Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:36:42.644Z [katib-controller] {"level":"info","ts":"2024-06-17T13:36:42Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:36:42.647Z [katib-controller] {"level":"info","ts":"2024-06-17T13:36:42Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:38:07.977Z [katib-controller] {"level":"info","ts":"2024-06-17T13:38:07Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:38:07.980Z [katib-controller] {"level":"info","ts":"2024-06-17T13:38:07Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:45:30.652Z [katib-controller] {"level":"info","ts":"2024-06-17T13:45:30Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:45:30.655Z [katib-controller] {"level":"info","ts":"2024-06-17T13:45:30Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:45:44.802Z [katib-controller] {"level":"info","ts":"2024-06-17T13:45:44Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:45:44.807Z [katib-controller] {"level":"info","ts":"2024-06-17T13:45:44Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:50:06.794Z [katib-controller] {"level":"info","ts":"2024-06-17T13:50:06Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}
2024-06-17T13:50:06.797Z [katib-controller] {"level":"info","ts":"2024-06-17T13:50:06Z","logger":"controller-runtime.certwatcher","msg":"Updated current TLS certificate"}

I visit http://<ip>/cos-grafana/explore to explore the logs and see:

Duplicated logs are also visible with kubectl, so if that's an issue we should report it, but fix by this PR.

[DnPlas]

It is looking really good, just a tiny nit. I will run some manual tests and report my findings. Thanks @rgildein !

[DnPlas]

I have run both the integration tests and the manual tests. Thanks @rgildein !

EDIT: I approved the PR, but there is a conflict with a file. Please rebase your branch and I can re-approve if needed.

[DnPlas]

Thanks @rgildein !