fix(gitlab): disable KAS at global level to stop Sidekiq NotifyGitPushWorker errors

The existing `global.appConfig.gitlab_kas.enabled: false` only affected
the KAS subchart config but was ignored by the chart template that
generates gitlab.yml. Adding `global.kas.enabled: false` properly sets
`gitlab_kas.enabled: false` in gitlab.yml and removes the orphaned
gitlab-kas Service, stopping ~5 GRPC::Unavailable errors per git push.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

infra/k8s/gitlab/values.yaml

@@ -4,6 +4,8 @@
 
 global:
   edition: ce
+  kas:
+    enabled: false
   hosts:
     domain: fxhnt.ai
     gitlab: