feat!: remove the postgresql sub-chart

With `cloudnativePG` in place, the bundled Bitnami `postgresql` sub-chart is the second in-chart way to run a
database, and the worse one. It is a single, non-HA instance without failover, backup or managed major-version
upgrades, and it ships images that Bitnami no longer distributes freely. Keeping it around means maintaining two
code paths for the same job, including the mutual-exclusion assertion between both dependencies and a second set
of DNS, credential and image helpers.

Removing it leaves exactly two supported choices: a CloudNativePG `Cluster` rendered by this chart, or an
external database configured via `gitea.config.database`. Both scale from a single instance to a HA setup -
`cloudnativePG.instances=1` covers the use case the `postgresql` sub-chart served - so nothing is lost besides
the duplication.

BREAKING CHANGE: The `postgresql` sub-chart and all `postgresql.*` values have been removed. There is no
in-place migration path: dump the database of the old `postgresql` release with `pg_dump`, remove the
`postgresql` values, deploy the chart with `cloudnativePG.enabled=true` and restore the dump. Alternatively
point `gitea.config.database` at an externally managed database. Setting `postgresql` now fails the release with
a pointer to the changelog.

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

templates/_helpers.tpl

@@ -180,12 +180,6 @@ app.kubernetes.io/instance: {{ .Release.Name }}
 {{- end -}}
 {{- end -}}
 
-{{- define "postgresql.dns" -}}
-{{- if (index .Values "postgresql").enabled -}}
-{{- printf "%s-postgresql.%s.svc.%s:%g" .Release.Name .Release.Namespace .Values.clusterDomain .Values.postgresql.global.postgresql.service.ports.postgresql -}}
-{{- end -}}
-{{- end -}}
-
 {{- define "valkey.dns" -}}
 {{- if (index .Values "valkey").enabled -}}
 {{- printf "redis://:%s@%s-valkey.%s.svc.%s:%g/0?pool_size=100&idle_timeout=180s&" (index (index .Values "valkey").auth.aclUsers "default").password .Release.Name .Release.Namespace .Values.clusterDomain (index .Values "valkey").service.port -}}
@@ -450,15 +444,6 @@ https
     {{- $_ := set .Values.gitea.config.database "NAME"      .Values.cloudnativePG.credentials.database -}}
     {{- $_ := set .Values.gitea.config.database "USER"      .Values.cloudnativePG.credentials.username -}}
   {{- end -}}
-  {{- if (index .Values "postgresql" "enabled") -}}
-    {{- $_ := set .Values.gitea.config.database "DB_TYPE"   "postgres" -}}
-    {{- if not (.Values.gitea.config.database.HOST) -}}
-      {{- $_ := set .Values.gitea.config.database "HOST"      (include "postgresql.dns" .) -}}
-    {{- end -}}
-    {{- $_ := set .Values.gitea.config.database "NAME"      .Values.postgresql.global.postgresql.auth.database -}}
-    {{- $_ := set .Values.gitea.config.database "USER"      .Values.postgresql.global.postgresql.auth.username -}}
-    {{- $_ := set .Values.gitea.config.database "PASSWD"    .Values.postgresql.global.postgresql.auth.password -}}
-  {{- end -}}
 {{- end -}}
 
 {{- define "gitea.container-additional-mounts" -}}

templates/deprecation.yaml

@@ -95,6 +95,11 @@
     {{- fail "`openshift.hostUsers` does no longer exist. Please refer to the changelog and configure `deployment.hostUsers` instead." -}}
   {{- end -}}
 
+  {{/* POSTGRESQL */}}
+  {{- if index .Values "postgresql" -}}
+    {{- fail "`postgresql` does no longer exist. Please refer to the changelog and configure `cloudnativePG` instead, which requires the CloudNativePG operator to be installed in the cluster." -}}
+  {{- end -}}
+
   {{/* POSTGRESQL HA */}}
   {{- if index .Values "postgresql-ha" -}}
     {{- fail "`postgresql-ha` does no longer exist. Please refer to the changelog and configure `cloudnativePG` instead, which requires the CloudNativePG operator to be installed in the cluster." -}}

templates/secret_config.yaml

@@ -21,11 +21,6 @@ data:
 
 {{- define "gitea.config.assertions" -}}
 
-  {{- /*assert that only one PG dep is enabled */ -}}
-  {{- if and (.Values.postgresql.enabled) (.Values.cloudnativePG.enabled) -}}
-    {{- fail "Only one of postgresql or cloudnativePG can be enabled at the same time." -}}
-  {{- end }}
-
   {{- /* multiple replicas assertions */ -}}
   {{- if gt (.Values.deployment.replicas | int) 1 -}}
     {{- if .Values.gitea.config.cron -}}