Fixes ISSUE-47174. Simplify & speed up calling generate.entities*
Change GenerateEntitiesTask to directly to the work in its main method instead of calling into AntExecutor and getting called again as an ant task. That simplifies both the build.xml & src/build.xml by removing the additional generate.entities.quick.forked target as well as simplifes the java code slightly. Extra benefit is shaving of 2-3 seconds of runtime of generate.entities.quick call which is called indirectly by various other build tasks. Side-effect: Stop supporting the obsolete friendlyWarning flag which is not set anymorr after the MMC rebuild popup removal.