build: clear 'requires' section in features.json

These files are only referenced in a test and the actual files don't exist in this repository. The jars and dependencies are all managed by the api-client BOM

https://github.com/googleapis/google-api-java-client-services/blob/4ba8ff880ea4acfe490510917941a82854e47fd3/generator/tests/configuration_test.py#L125-L148

Author: diegomarquezp