fix: use correct external DB username and allow dbinit for shared MySQL

- Change database.username from "hades_user" to "mysql_user" to match
  the shared MySQL user created by Backstage environment provisioning
- Remove mysql.enabled=true condition from dbinit job so SQL migrations
  run against external/shared MySQL databases too

Without these fixes, deploying hades with mysql.enabled=false (Backstage
shared MySQL) causes access denied because hades_user doesn't exist in
the shared MySQL, and dbinit is skipped so no tables are created.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hades/templates/job-dbinit.yaml

@@ -1,4 +1,4 @@
-{{- if and .Values.dbInit.enabled (eq (printf "%v" .Values.mysql.enabled) "true") }}
+{{- if .Values.dbInit.enabled }}
 apiVersion: batch/v1
 kind: Job
 metadata:

hades/values.yaml

@@ -123,7 +123,7 @@ database:
   host: ""  # Will be set to mysql.fullname if mysql.enabled=true
   port: "3306"
   name: "hades_db"
-  username: "hades_user"
+  username: "mysql_user"
   password: ""  # Leave empty to auto-generate
   # For external database, set mysql.enabled=false and configure above values