Captures follow up work to T333211. This work should be done in the weeks leading up to the 1.44 release.
#TODO
[x] Run a new user notice (see T385346 for original) telling editors if they haven't followed instructions in T385346 they will lose the special page link.
[x] Make sure user notice identifies all MediaWiki:Sidebar pages that exist without the special page link to clarify who is impacted.
> Done in {T388927}
[] Remove the Skin::appendSpecialPagesLinkIfAbsent method in the first deploy of 1.45. https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1124223
[] Write a patch that removes Skin::appendSpecialPagesLinkIfAbsent to avoid production warnings and merge alongside https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1124223 **TODO**
[] Backport https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1124223 to 1.44