Remove tap-gtester, rely on GLib 2.38+ built-in TAP output instead
GLib 2.62+ outputs TAP by default, which breaks the tap-gtester script's expectations. In older GLib versions since 2.38, --tap is an opt-in to the TAP output mode, so use that.
This is essentially the same issue as https://github.com/cockpit-project/cockpit/pull/11998 (cockpit was the source of the tap-gtester script), gcr!19 (merged), and libsecret!5 (merged).
Bug-Debian: https://bugs.debian.org/940157
Edited by Simon McVittie