Add releaseTest option to CI script (elastic/x-pack-elasticsearch#2482)
Add releaseTest option to CI script (elastic/x-pack-elasticsearch#2482)

This option runs a normal check but with `-Dsnapshot=false` (the flag
used to indicate a release build).

Related to https://github.com/elastic/infra/issues/2759 and
https://github.com/elastic/infra/issues/2739 from the ES side.

Original commit: elastic/x-pack-elasticsearch@e674e68905186792c724c0fb925dbae3caf3e9e1

nknize/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,coding0011/elasticsearch,HonzaKral/elasticsearch,uschindler/elasticsearch,GlenRSmith/elasticsearch,uschindler/elasticsearch,GlenRSmith/elasticsearch,uschindler/elasticsearch,coding0011/elasticsearch,robin13/elasticsearch,gfyoung/elasticsearch,gfyoung/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,nknize/elasticsearch,gfyoung/elasticsearch,scorpionvicky/elasticsearch,coding0011/elasticsearch,coding0011/elasticsearch,coding0011/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,HonzaKral/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,scorpionvicky/elasticsearch,robin13/elasticsearch,gingerwizard/elasticsearch,robin13/elasticsearch,nknize/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,gfyoung/elasticsearch,uschindler/elasticsearch,uschindler/elasticsearch