Prow gerrit: deprecating default label logs Debug instead of Warn
Prow gerrit: deprecating default label logs Debug instead of Warn

These logs are only monitored by prow operators, who normally don't control which label a prow job reports to. Log on warning level caused spam in log stream

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