e2scrub_fail: move executable script to /usr/libexec

e2scrub_fail: move executable script to /usr/libexec

Per FHS 3.0, non-PATH executable binaries are supposed to live under
/usr/libexec, not /usr/lib.  e2scrub_fail is an executable script, so
move it to libexec in case some distro some day tries to mount /usr/lib
as noexec or something.  Also, there's no reason why these scripts need
to be put under an arch-dependent path.

Cc: Neal Gompa <neal@gompa.dev>
Link: https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch04s07.html
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Link: https://lore.kernel.org/r/20231231203903.GC36164@frogsfrogsfrogs
Signed-off-by: Theodore Ts'o <tytso@mit.edu>