Remove unused resources

Signed-off-by: Álvaro Brey Vilas <alvaro.brey@nextcloud.com>

app/src/main/res/values/strings.xml

@@ -1008,13 +1008,10 @@
     <string name="pdf_zoom_tip">Tap on a page to zoom in</string>
     <string name="storage_permission_full_access">Full access</string>
     <string name="storage_permission_media_read_only">Media read-only</string>
-    <string name="file_locked">This file is locked</string>
     <string name="lock_file">Lock file</string>
     <string name="unlock_file">Unlock file</string>
     <string name="error_file_lock">Error changing file lock status</string>
-    <string name="file_lock_dialog_title">Lock details</string>
     <string name="locked_by">Locked by %1$s</string>
     <string name="locked_by_app">Locked by %1$s app</string>
     <string name="lock_expiration_info">Expires: %1$s</string>
-    <string name="file_not_locked">File is not locked</string>
 </resources>