kernel-install: check all entry candidates first, then check existence of $pref/loader/entries only once
    
    If we have multiple entries in $ENTRY_TOKEN_SEARCH, and $pref/loader/entries
    exists, then previously we would always exit after the first candidate and
    ignore the second and later candidates.
    
    Follow-up for 1b43f868934e971480249a6e0fa2f45da906ea2e.