kdumpctl: Fix misleading message and erratic reboot in reset_crashkernel
    
    Resolves: RHEL-42442
    Resolves: RHEL-22171
    Upstream: RHEL-only
    
    This bug was fixed upstream in 574f8f5 ("kdumpctl: Simplify fadump
    handling in reset_crashkernel"). Backporting this commit to RHEL9 would
    require also to backport other commits that would change the behavior of
    reset-crashkernel, e.g. no longer setting the default kernel command
    line in the grub config. These changes are too invasive for RHEL9. Thus
    go with a minimalistic RHEL-only fix.
    
    Signed-off-by: Philipp Rudo <prudo@redhat.com>