Fixed PXB-2693 - initialize submodules (#1439)
Fixed PXB-2693 - initialize submodules (#1439)

https://jira.percona.com/browse/PXB-2693

Adjust PXC scripts to also initialize PXB submodules.
Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines