feat(deployment)!: move schedulerName to deployment.schedulerName

The top-level `schedulerName` value only ever configured the pod spec of the Gitea Deployment, but was declared
next to chart-wide settings. Moving it into the `deployment` dict completes the consolidation already done for
`affinity`, `dnsConfig`, `nodeSelector`, `priorityClassName`, `resources`, `tolerations` and
`topologySpreadConstraints`, so every pod scheduling setting now lives in one predictable place.

A deprecation check fails the release when the removed top-level value is still set. Silently ignoring it would
be hard to debug: the pod would fall back to the `default-scheduler` without any warning, bypassing the custom
scheduler the user relies on for placement decisions such as storage locality.

BREAKING CHANGE: `schedulerName` no longer exists. Use `deployment.schedulerName` instead. Installations that
still set `schedulerName` will fail unless `checkDeprecation` is set to `false`.

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

unittests/helm/deployment/basic.yaml

@@ -139,6 +139,19 @@ tests:
       - equal:
           path: spec.template.spec.priorityClassName
           value: high-priority
+  - it: schedulerName is undefined
+    template: templates/gitea/deployment.yaml
+    asserts:
+      - notExists:
+          path: spec.template.spec.schedulerName
+  - it: schedulerName is defined
+    template: templates/gitea/deployment.yaml
+    set:
+      deployment.schedulerName: stork
+    asserts:
+      - equal:
+          path: spec.template.spec.schedulerName
+          value: stork
   - it: tolerations are undefined
     template: templates/gitea/deployment.yaml
     asserts: