Fixed PXB-2693 - initialize submodules (#1398)
Fixed PXB-2693 - initialize submodules (#1398)

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

Adjusted checkout script to also initialize submodules.
Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines,Percona-Lab/jenkins-pipelines