feat(helm): Add health probes to write

[lindhe]

What this PR does / why we need it:

This change adds configurable livenessProbe and startupProbe to the loki container in the write pods.

Which issue(s) this PR fixes:

Not sure.

Special notes for your reviewer:

Partially replaces https://github.com/grafana/loki/pull/15359

Checklist

• [x] Reviewed the CONTRIBUTING.md guide (required)
• [x] Documentation added
• [ ] Tests updated
• [x] Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• [ ] Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• [ ] If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[lindhe]

Rebased on main to see if that fixes the test errors. I'm not missing something here, right? Feels like these errors are not my work…

[JStickler]

@lindhe There's an issue with that particular test. We're looking at a fix.