[zookeeper] remove backports for releases older than oldstable#1170

cjac wants to merge 1 commit intoGoogleCloudDataproc:mainGoogleCloudDataproc/initialization-actions:mainfrom

cjac:oldoldstable-backports-removal-zookeepercjac/initialization-actions:oldoldstable-backports-removal-zookeeperCopy head branch name to clipboard