tests: Fix failing test_moosefs_upgrade

After one of the last changes to lizardfs-probe it can no loger be used
with MoozeFS master server, so lizardfs_wait_for_all_ready_chunkservers
function used it out testing framework no longer works correctly for
this test. This commit replaces it with "sleep 3" for all tests which
use MooseFS master server.

Change-Id: I5810e2b2549a08e5facd78904c64691c9b55f8ac