Update the packages and file names to reflect the new postinst recipe.
Fix a sh syntax error in the run_serial file exists test which was hidden by a
logic problem in the status code.
Remove the older test_verify_postinst as it's effectively a subset of
test_postinst_rootfs_and_boot, and doesn't work: when booting under systemd the
strings it searches for are not output to the console, but the test still
passes.
Signed-off-by: Ross Burton <ross.burton@intel.com>
