99memstrack: hook script should not call exit
    
    With memstrack module, rd.break may not work because the hook scripts
    are sourced, not executed, so the exit call will make pre-pivot queue
    exit early. See 98dracut-systemd/dracut-pre-pivot.sh, everything after
    "source_hook cleanup" will be ignored.
    
    Replace with return instead.
    
    Credits go to Lukas Nykryn <lnykryn@redhat.com> who helped discover and
    debug this issue.
    
    Signed-off-by: Kairui Song <kasong@redhat.com>
    (cherry picked from commit 424f01e2a0ac0b329e68eb63048cf0d6d9c74d37)
    
    Resolves: #1829528
    
    patch_name: 0083.patch
    present_in_specfile: true
    location_in_specfile: 83
    squash_commits: true