[test][conftest] Create a dummy environment cache file

Will be used by the ExperimentEditor tests
2 jobs for 218_docker_environments_handling in 20 minutes and 12 seconds (queued for 4 seconds)
Status Name Job ID Coverage
  Build
passed build_linux_36 #165695
docker-build

00:05:57

passed build_macosx_36 #165696
macosx

00:20:10