Part of https://github.com/ooni/probe/issues/1753.
While there, introduce a rule by which, if the branch is named `fullbuild` we run all possible builds. It helps to test all the builds without creating a release branch. Because release branches are protected, they cannot be deleted easily. On the contrary, the `fullbuild` branch can easily be disposed of.
I am not 100% sure I was able to fix all the cases in which we
need higher permissions than the strict default.
At least, I tried.
It may be reasonable to make an interim release to check whether I
successfully fixed all the cases.
Ref issue: https://github.com/ooni/probe/issues/2154
