Updates for containers config

[jmckulk]

Description

Assorted changes to update containers related dashboards and configuration.

• Pull the query stats WAL panel into containers dashboards

• Update the expr in Grafana query_statistics dashboard panel for WAL

• Use PROMETHEUS data source name in dashboards

• Simplify the Prometheus config to remove unnecessary options

  • Remove redundant labels (previously merged in #300)
  • Provide comments around relabel_configs
  • Use a kube discovery selector for the alertmanager and exporter pods

• [ ] Bugfix

• [x] Enhancement

• [ ] Breaking Change

• [ ] Documentation

Testing

None of the testing listed below is optional.

• Installation method:
  • [ ] Binary install from source, version:
  • [ ] OS package repository, distro, and version:
  • [ ] Local package server, version:
  • [ ] Custom-built package, version:
  • [x] Other: Container install with PGO
• [x] PostgreSQL, Specify version(s): 15
• [ ] docs tested with hugo version(s):

Code testing

Have you tested your changes against:

• [ ] RedHat/CentOS
• [ ] Ubuntu
• [ ] SLES
• [ ] Not applicable

If your code touches postgres_exporter, have you:

• [ ] Tested against all versions of PostgreSQL affected
• [ ] Ensure that exporter runs with no scrape errors
• [ ] Not applicable

If your code touches node_exporter, have you:

• [ ] Ensure that exporter runs with no scrape errors
• [ ] Not applicable

If your code touches Prometheus, have you:

• [x] Ensured all configuration changes pass promtool check config
• [x] Ensured all alert rule changes pass promtool check rules
• [x] Prometheus runs without issue
• [x] Alertmanager runs without issue
• [ ] Not applicable

If your code touches Grafana, have you:

• [x] Ensured Grafana runs without issue
• [x] Ensured relevant dashboards load without issue
• [ ] Not applicable

Checklist:

• I have made corresponding changes to:
  • [ ] the documentation
  • [ ] the release notes
  • [ ] the upgrade doc

[benjaminjb]

This would certainly streamline some of the work that goes into containers monitoring for the operator stack.