revert(ldap): remove CTL-specific AD connection prefill

The prior quick task (260707-csw) pre-filled the LDAP connection form
with one customer's specific Active Directory values (balios.ctl.local,
dc=ctl,dc=local) and a matching bind-DN hint. User clarified this was
never wanted -- Tessera is a generic multi-tenant product, and baking
one customer's infrastructure into the shared admin UI is wrong,
especially since a `dcdown -v` reinstall surfaced it unexpectedly as
seemingly-baked-in defaults on a fresh system.

Reverted to blank fields with generic example placeholders
(ldap.example.com / dc=example,dc=com / cn=admin,dc=example,dc=com),
matching the form's state before that change. Removed the now-unused
bindDnHint i18n key.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/src/messages/en.json

@@ -293,7 +293,6 @@
       "testFailed": "Connection failed",
       "enable": "Enabled",
       "disable": "Disabled",
-      "bindDnHint": "AD format: domain\\username (e.g. ctl\\serviceaccount), not DN notation.",
       "fieldMapping": {
         "title": "Field mapping",
         "add": "Add mapping",