metrics: support workload identity
metrics: support workload identity

moving the job that runs this from a bootstrap-based prowjob (which
performs this gcloud auth check before invoking its arguments) to a
decorated job (which leaves this responsibility to the command being
invoked)

kubernetes/test-infra,monopole/test-infra,monopole/test-infra,michelle192837/test-infra,monopole/test-infra,kubernetes/test-infra,dims/test-infra,monopole/test-infra,BenTheElder/test-infra,michelle192837/test-infra,cjwagner/test-infra,michelle192837/test-infra,dims/test-infra,cjwagner/test-infra,fejta/test-infra,dims/test-infra,cblecker/test-infra,jessfraz/test-infra,BenTheElder/test-infra,kubernetes/test-infra,jessfraz/test-infra,cblecker/test-infra,jessfraz/test-infra,BenTheElder/test-infra,jessfraz/test-infra,monopole/test-infra,cblecker/test-infra,fejta/test-infra,cjwagner/test-infra,cjwagner/test-infra,cblecker/test-infra,kubernetes/test-infra,jessfraz/test-infra,michelle192837/test-infra,fejta/test-infra,dims/test-infra,fejta/test-infra,fejta/test-infra,BenTheElder/test-infra,michelle192837/test-infra,jessfraz/test-infra,dims/test-infra,monopole/test-infra,BenTheElder/test-infra,michelle192837/test-infra,kubernetes/test-infra,cblecker/test-infra,cblecker/test-infra,fejta/test-infra,cjwagner/test-infra,kubernetes/test-infra,dims/test-infra,cjwagner/test-infra,BenTheElder/test-infra