_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>

tests/_boot_to_anaconda.pm

@@ -89,7 +89,7 @@ sub run {
         # we get anaconda logs. sleep a bit first so we don't get a
         # match for the installer bootloader if it hangs around for a
         # while after do_bootloader finishes (in PXE case it does)
-        sleep 20;
+        sleep 60;
         assert_screen "bootloader", 1800;
     }
     else {