remove 'python' from test jobs since obsolete
also, 'python3' gets installed with the extended job (https://gitlab.cern.ch/mro/common/tools/gitlab-ci-utils/-/blob/master/ci/scripts/gitlab-ci-node.yml#L124)
also, 'python3' gets installed with the extended job (https://gitlab.cern.ch/mro/common/tools/gitlab-ci-utils/-/blob/master/ci/scripts/gitlab-ci-node.yml#L124)