Add config.stopBubbling to the root lombok.config

Append config.stopBubbling = true to the root lombok.config, so that Lombok reads the project's configuration and nothing else. Lombok resolves a key by walking up from the directory of the Java file it is compiling and does not stop at the project, so without this key a lombok.config in a parent directory of the checkout takes part in the build. Note that this cuts the project off from such a file whether or not it was meant to be read. Nothing is added when the key is already declared, whatever value it is assigned or whether the root file declares it or imports it.