[FW][REM] developer/upgrade: remove outdated page

[fw-bot]

task-2613841

Forward-Port-Of: #1079

[robodoo]

Pull request status dashboard.

[fw-bot]

Ping @Donapi, @AntoineVDV
Cherrypicking 65cfe5e of source #1079 failed

stderr:

15:46:54.670647 git.c:344               trace: built-in: git cherry-pick 65cfe5e75ed06b80869775040655324a9da3b243
error: could not apply 65cfe5e7... [REM] developer/upgrade: remove outdated page
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'
----------
status:

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

[AntoineVDV]

@robodoo r+