Since lintcommit is a required check, it will always need to be run.
However, the lintcommit script is not designed to work on PRs that
doesn't target master branch (and it's not clear whether it's even
desirable).
To circumvent this we create a "dummy" lintcommit check that is run on
release branches that always passes, thus fulfilling the condition of
the required check.
(cherry picked from commit 0500804df5)
Github doesn't allow workflows to be run from the `github-actions`
account, which is the default account. This caused the CI on backport
PRs to not be run. The way to circumvent this is to use a token that
essentially "pretends" to be another user, which in turn triggers the CI
as desired.
Also run lintcommit on release branches as that is now a required check,
meaning it must always be run.
