The change c7c87909 has introduced an unconditional check
for wsrep cluster during bootstrap process whether is ready or not
and if it is not, bootstrap fails.
In kubernetes environment wsrep driver is set to none, cluster will
NEVER reach ready state hence causing kubernetes mariadb bootstrap job
failure.

Closes-Bug: #1623662

Change-Id: I0e6fc098861b7eeab544229d0b04a78fa498ddb9