ZOOKEEPER-4207: Remove extra checkout from Jenkinsfile
ZOOKEEPER-4207: Remove extra checkout from Jenkinsfile

I believe we don't need to add the git checkout to the "Steps" section. I cannot see it neither in owasp nor the PR jenkinsfiles. Also I see that master branch gets also checked out during our normal builds, so I hope this will fix it.

Target branches: master, branch-3.7, branch-3.6, branch-3.5

Author: Andor Molnar <andor@apache.org>

Reviewers: Enrico Olivelli <eolivelli@apache.org>

Closes #1600 from anmolnar/ZOOKEEPER-4207

maoling/zookeeper,arshadmohammad/zookeeper,maoling/zookeeper,apache/zookeeper,arshadmohammad/zookeeper,maoling/zookeeper,hanm/zookeeper,hanm/zookeeper,apache/zookeeper,hanm/zookeeper,apache/zookeeper,hanm/zookeeper,hanm/zookeeper,apache/zookeeper,hanm/zookeeper,arshadmohammad/zookeeper,arshadmohammad/zookeeper,arshadmohammad/zookeeper,maoling/zookeeper,apache/zookeeper,arshadmohammad/zookeeper,maoling/zookeeper,maoling/zookeeper,arshadmohammad/zookeeper,maoling/zookeeper,hanm/zookeeper,hanm/zookeeper,maoling/zookeeper,apache/zookeeper,apache/zookeeper,apache/zookeeper,arshadmohammad/zookeeper