Remove latest tag from tp33 branch

All Docker images on tp33 currently get the latest tag. We need to remove the tagging of latest from this branch before 3.4.0 is released as that will be tagged as latest from then on.

The tagging is already present on master. So it really only has to be removed from tp33 from both gremlin-server and gremlin-console pom.xml files.

This can only be done when we are sure that there will be no release of TinkerPop anymore for the tp33 that doesn't also include a release of version 3.4.0.