Revert "Compat: Upgrade admin notices to use Notices module at runtime"

[aduth]

Related: #11604
Closes #12243

This pull request seeks to effectively revert #11604 .

Notably, since this was included in published releases already, it has been done in such a way that it bumps the major versions of the edit-post and notices modules to reflect the fact that the revert is a breaking change.

Two commits from #11604 have been exempt from the revert (i.e. will remain in master):

• accb891
• abc7633

These were not strictly relevant to the addition of admin notices compatibility. Ideally, they would have been proposed as separate changes. In omitting them, they reduce the number of changes included in this revert.

Testing instructions:

Verify the inverse of the testing instructions outlined in #11604.

[aduth]

This never actually went through in #11604. See #11604 (comment) .

[youknowriad]

Should we close this? An alternative has been merged right?

[aduth]

@youknowriad #12444 was a safer "revert", while not actually being a proper revert. The code still lingers. The changes here would be more an actual revert. The public-facing interface changes are limited to the speak option in notices, which we could realistically keep around. The AdminNotices component, while noted in the changelog of edit-post@3.1.0, isn't actually exposed on the public interface of the module.

[gziolo]

#12243 is closed. It looks like the original issue was resolved. Does it mean that this PR can be closed, too?

[aduth]

There is still dead code left to be eliminated.

I may want to specifically revisit whether to remove the speak option, since there's some commitment for backwards-compatibility there.

[aduth]

There is still dead code left to be eliminated.

Not sure about the status of dead code these days, but the branch is long-stale, so I doubt it's much use in its current form, so will go ahead and close.