Remove the gradle cheatsheet (elastic/x-pack-elasticsearch#3708)
Remove the gradle cheatsheet (elastic/x-pack-elasticsearch#3708)

The cheatsheet was removed from the elasticsearch repo in
https://github.com/elastic/elasticsearch/pull/28113. This commit removes
it from xpack for the same reasons.

Original commit: elastic/x-pack-elasticsearch@267c5f818f1fe4f27e4056237023691f1387f3a9

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