Problem:- While running tests from wsrep suite , we include file have_wsrep.inc
or have_wsrep_enabled.inc , these file test wsrep plugin is ACTIVE or 'wsrep_on'
is ON. These select does not ensure that whether 'wsrep_ready' is ON , So that
we can process SQL queries. So sometimes we will get error like this
mysqltest: At line 81: query 'call mtr.check_testcase()' failed: 1047: WSREP has
not yet prepared node for application use  not ok

Solution:- In file have_wsrep.inc and have_wsrep_enabled.inc we will include
wait_until_ready.inc , which will wait untill 'wsrep_on' is on