MW-405 Remove wait_until_connected_again.inc from kill_galera.inc

kill_galera.inc can no longer rely on wait_until_connected_again.inc.
This is because wait_until_connected_again now tries to make sure
that the server it is connected eventually transition to ready
state. Whereas some tests may need to kill galera while the server
is in a non-primary view.

mysql-test/suite/galera/include/kill_galera.inc

 --echo Killing server ...
 
 # Write file to make mysql-test-run.pl expect the crash, but don't start it
---source include/wait_until_connected_again.inc
 --let $_server_id= `SELECT @@server_id`
 --let $_expect_file_name= $MYSQLTEST_VARDIR/tmp/mysqld.$_server_id.expect
 --exec echo "wait" > $_expect_file_name