Issue:
  During bootstrap, formula creates file in: /var/lib/mysql
  If galera replica has been broken for any reason, wsrep process
  calls xtrabackup to recover replica and wipes away everything in
  /var/lib/mysql with bootstrap flag as well.
  Now this node is not marked as deployed and galera state rerun
  would try to reprovision it and fail.

Fix:
  Create and check flag in: /etc/mysql/.galera_bootstrap

Prod-Related: PROD-22715
Closes-Bug: PROD-22715
Change-Id: I27db65e1161e22a462dfd273647de4edbe450373