core: fix the return value in order to make sure we don't dipatch method return too early
    
    Actually, it is the same kind of problem as in d910f4c . Basically, we
    need to return 1 on success code path in slice_freezer_action().
    Otherwise we dispatch DBus return message too soon.
    
    Fixes: #16050
    (cherry picked from commit 2884836e3c26fa76718319cdc6d13136bbc1354d)
    
    Related: #1830861
    
    patch_name: 0426-core-fix-the-return-value-in-order-to-make-sure-we-d.patch
    present_in_specfile: true
    location_in_specfile: 426
    squash_commits: true