refactor(templates): rename template files to match rendered resource kinds

The files in templates/gitea/ used a mix of naming styles: lowercase concatenations
(poddisruptionbudget.yaml, serviceaccount.yaml, servicemonitor.yaml, pvc.yaml), camelCase
(httpService.yaml, sshService.yaml) and kind-suffixed names (gpg-secret.yaml, metrics-secret.yaml).
It was therefore not obvious from a file name which Kubernetes resource it renders, and the naming
contradicted the camelCase convention the Gateway API templates already follow.

Files are now named after the kind they render, with a lowercase suffix distinguishing several
resources of the same kind:

  config.yaml              -> secret_config.yaml + secret_inlineConfig.yaml
  gpg-secret.yaml          -> secret_gpg.yaml
  init.yaml                -> secret_init.yaml
  metrics-secret.yaml      -> secret_metrics.yaml
  httpService.yaml         -> service_http.yaml
  sshService.yaml          -> service_ssh.yaml
  poddisruptionbudget.yaml -> podDisruptionBudget.yaml
  pvc.yaml                 -> persistentVolumeClaim.yaml
  serviceaccount.yaml      -> serviceAccount.yaml
  servicemonitor.yaml      -> serviceMonitor.yaml

config.yaml rendered two Secrets from a single file, which forced every unit test to address them via
documentIndex. It is split so that each file renders exactly one resource.

The rendered manifests are unchanged; only file names and the references to them were touched. This
includes the checksum/config annotation in deployment.yaml and all helm unit test suites. The HA guard
assertions had to move from deployment.yaml to secret_config.yaml: Helm sorts templates in reverse
alphabetical order, so secret_config.yaml is now rendered before deployment.yaml and the fail() is
reported for that file directly instead of bubbling up through the include chain of the Deployment.

Users relying on the template paths (e.g. `helm template --show-only` or post-renderers) have to
adjust to the new file names.

Co-authored-by: Copilot <copilot@github.com>

unittests/helm/deployment/openshift.yaml

@@ -4,7 +4,7 @@ release:
   namespace: testing
 templates:
   - templates/gitea/deployment.yaml
-  - templates/gitea/config.yaml
+  - templates/gitea/secret_config.yaml
 tests:
   - it: renders openshift-compatible defaults for chart-managed containers
     template: templates/gitea/deployment.yaml