test(16-04): remove orphaned ldapBind i18n keys, add D-07 regression tests

Delete the admin.groups.ldapBind.* subtree (hint/bound/unbind/
searchPlaceholder/discoverError/noResults) from de.json and en.json —
fully orphaned since GroupFormModal.tsx no longer has an AD-binding
codepath. admin.groups.ldapBinding (column header) and every other
admin.groups.* key are untouched; key sets stay in parity across both
languages.

Test file's translation stub loses the same dead ldapBind block and
gains the seven Task 1 keys. Two new cases lock down D-07: opening the
create dialog issues no /ldap/groups request, and editing an imported
group renders a disabled name input plus the internal-name field
instead of any AD-search UI.

apps/web/src/messages/en.json

@@ -410,14 +410,6 @@
       "internalNameHint": "Never changed by the sync. If left empty, the interface shows the AD name instead.",
       "createLdapHint": "AD groups are imported in the LDAP area, not created here.",
       "goToLdap": "Go to LDAP area",
-      "ldapBind": {
-        "hint": "Choose an AD group from the list to sync membership automatically.",
-        "bound": "Bound to: {ldapDn}",
-        "unbind": "Remove binding",
-        "searchPlaceholder": "Search AD groups...",
-        "discoverError": "Could not load AD groups. Please try again.",
-        "noResults": "No AD groups found."
-      },
       "members": {
         "title": "Members",
         "remove": "Remove member",