fix(helm): Websocket related proxy_set_header to locations back to resolve high CPU usage.

[jkroepke]

What this PR does / why we need it:

Reverts #18414

With #18105 we now have the ability to set proxy_set_headers on each location.

In a default configuration, I also not see any breaking change here. However, if end-users has configure additional authentications method, like mTLS, they may hay move configuration from gateway.nginxConfig.httpSnippet to gateway.nginxConfig.locationSnippet as well.

Which issue(s) this PR fixes:
Fixes #18753

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
• 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

[Jayclifford345]

Hey @jkroepke would you mind running :)

make helm-docs

[jkroepke]

@Jayclifford345 done! + Adding a warning for end-users with customized / non-default auth settings.

[Jayclifford345]

LGTM