MDL-70494 mod_forum: Deprecate privacy strings.

Doesn't seem they were ever used.

mod/forum/lang/en/deprecated.txt

@@ -3,3 +3,6 @@ completiondiscussionsgroup,mod_forum
 completiondiscussionshelp,mod_forum
 completionrepliesgroup,mod_forum
 completionreplieshelp,mod_forum
+privacy:request:delete:discussion:name,mod_forum
+privacy:request:delete:post:message,mod_forum
+privacy:request:delete:post:subject,mod_forum

mod/forum/lang/en/forum.php

@@ -600,9 +600,6 @@
 $string['privacy:metadata:preference:trackforums'] = 'Whether to enable read tracking.';
 $string['privacy:postwasread'] = 'This post was first read on {$a->firstread} and most recently read on {$a->lastread}';
 $string['privacy:readtrackingdisabled'] = 'You have chosen to not track posts you have read within this forum.';
-$string['privacy:request:delete:discussion:name'] = 'Delete at the request of the author';
-$string['privacy:request:delete:post:message'] = 'The content of this post has been deleted at the request of its author.';
-$string['privacy:request:delete:post:subject'] = 'Delete at the request of the author';
 $string['privacy:subscribedtoforum'] = 'You are subscribed to this forum.';
 $string['privatereply'] = 'Reply privately';
 $string['privatereply_help'] = 'When you reply privately, your post is also visible to users with the capability to view private replies, such as teachers.';
@@ -798,3 +795,8 @@
 $string['completiondiscussionshelp'] = 'requiring discussions to complete';
 $string['completionrepliesgroup'] = 'Require replies';
 $string['completionreplieshelp'] = 'requiring replies to complete';
+
+// Deprecated since Moodle 4.5.
+$string['privacy:request:delete:discussion:name'] = 'Delete at the request of the author';
+$string['privacy:request:delete:post:message'] = 'The content of this post has been deleted at the request of its author.';
+$string['privacy:request:delete:post:subject'] = 'Delete at the request of the author';

mod/forum/rsslib.php

@@ -360,8 +360,8 @@ function forum_rss_feed_contents($forum, $sql, $params, $context) {
                     $item->author = get_string('forumauthorhidden', 'forum');
                 } else {
                     // This is a post which has been deleted.
-                    $item->title = get_string('privacy:request:delete:post:subject', 'mod_forum');
-                    $message = get_string('privacy:request:delete:post:subject', 'mod_forum');
+                    $item->title = get_string('forumsubjectdeleted', 'mod_forum');
+                    $message = get_string('forumbodydeleted', 'mod_forum');
                     $item->author = get_string('forumauthorhidden', 'forum');
                 }
             } else {