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@1143f68a5d9580dca17a773ed2e80332e7b5d920

vroyer/elassandra,strapdata/elassandra,vroyer/elassandra,strapdata/elassandra,vroyer/elassandra,strapdata/elassandra,strapdata/elassandra,strapdata/elassandra