teams.ci: remove wolfgangwalther
I didn't achieve everything I had hoped for, but certainly GHA CI is in
a better state than half a year ago.
It makes no sense to have Philip as a single point of failure, so I just
added all members as maintainers - we are all committers anyway, there
is no point in making a difference here.
(cherry picked from commit 7f5e5917b83a4a95d949c1803625839ce24ae32f)
![github-actions[bot]](https://avatars.githubusercontent.com/in/15368?v=4&s=60)