[TASK] Add branch alias for system extensions

To ease installation of master versions of
system extensions from subtree splitted repos,
we add a branch alias to all of them.

Resolves: #81979
Releases: master
Change-Id: Ic7f4aa4762286e4e881447d6ecdbead411e6635f
Reviewed-on: https://review.typo3.org/53600


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>