flatpak completions gate some features behind checks like
test $flatpakversion -gt 1.2
which does a floating point comparison, which is different
from version comparison.
Most of these version checks are irrelevant anyway because they check for
a version that's not even in Debian oldstable. The only one that might be
relevant is a check for version 1.5 but that only gates some extra subcommands;
there's little harm in providing them too.
So let's just remove the version check.
Hopefully fixes#9341 (untested)
Note that flatpak upstream provides a completion file too - but it's shadowed
by ours on my system. This is a tricky issue for another day.
