_boot_to_anaconda: extend the sleep before bootloader re-check
    
    What's supposed to happen here is the `do_bootloader` invocation
    a few lines back boots to the installer, then here, we wait for
    the install to complete and the system to reboot, and match the
    bootloader again. However, on PXE installs, the bootloader screen
    can hang around for quite a long time here, and if it does, we
    can match it again before the installer starts up, and move on
    too early. Hence the sleep.
    
    It seems on current Rawhide 20 seconds isn't long enough - we're
    still matching the installer bootloader after the sleep, see
    e.g. https://openqa.stg.fedoraproject.org/tests/2431660#step/_boot_to_anaconda/3
    This is causing the test to almost always fail (it'll only pass
    if the install+reboot takes less than five minutes). Let's bump
    it to 60 seconds and hope that's long enough.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>