Make `dump_to_rootfs` wait for 90s for real
    
    Previous commit da6b280 ('Cleanup dead systemd services before start sysroot.mount')
    is not enough for fixing bz1972463. Coiby found a new issue that never
    saw before, this patch fixes it.
    
    Resolves: bz1972463
    Conflict: None
    Upstream: Fedora
    
    commit 660cf4ac03f29c42801725908cac156151159d2b
    Author: Kairui Song <kasong@redhat.com>
    Date:   Tue Jul 20 13:41:08 2021 +0800
    
        Make `dump_to_rootfs` wait for 90s for real
    
        When `failure_action` is set to `dump_to_rootfs`, the message:
        "Waiting for rootfs mount, will timeout after 90 seconds"
        is actually wrong. Kdump will simply call `systemctl start sysroot.mount`,
        but the timeout value of sysroot.mount depends on the unit service and
        dracut parameters. And by default, dracut will set
        JobRunningTimeoutSec=0 and JobTimeoutSec=0 for the device units,
        which means it will wait forever. (see wait_for_dev function in dracut)
    
        For some devices, this can be fixed by setting rd.timeout=90. But when
        initqueue is set enabled during initramfs build, dracut will force set
        timeout for host devices to `0`. (see 99base/module-setup.sh).
    
        Depending on dracut / systemd can make things unpredictable and break as
        parameters or code change. To make things easy to understand and
        maintain, just call `systemctl` with `--no-block` params, and implement
        a standalone wait loop.  Now `dump_to_rootfs` will actually wait for
        90s then timeout.
    
        Signed-off-by: Kairui Song <kasong@redhat.com>
        Acked-by: Coiby Xu <coxu@redhat.com>
    
    Signed-off-by: Kairui Song <kasong@redhat.com>