[Dev] [PATCH] QA: Replace shebang with env-variant in 'parabola-vmbootstrap'

[bill-auger]

LGTM - but the parabola-vmbootstrap tool was not written with
other distros in mind - it probably would not run on guix
without more tweaking, of the parabola-vmbootstrap scripts, and
of the guix host system

for example, it requires some arch- and parabola- specific tools
and libraries (namely: 'arch-install-scripts', 'librelib', and
'pacman')

the scripts also include some other hard-coded bits, like how it
locates installed binaries for qemu_static targets, and other
system files which are expected to exist, such as /bin/true and
/dev/zero