tests: Hide unnecessary trace output from the test logs
tests: Hide unnecessary trace output from the test logs

We use some BASH_XTRACEFD hackery to hide the trace output from
the internals of the assert (and ok) functions, so that the
log output can focus on what is important, i.e. what asserts are
checked and what errors do they print.

flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak