feat(helm): Add support for STS Endpoint and init containers for query-frontend, query-scheduler and distributor

[tiagoposse]

What this PR does / why we need it:

This PR adds support for the sts_endpoint config introduced in #13518, and support for extra init containers for query-frontend, query-scheduler and distributor. This is helpful for several use cases. In my case this allows using self-signed certificates for the STS endpoint.

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• 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
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• 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

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