Make verify_boilerplate print repo-relative paths.
Make verify_boilerplate print repo-relative paths.

Bazel absolute paths are *really* long.

/bazel-scratch/.cache/bazel/_bazel_root/27a95fe2fc68aa1195ddf1a4bbaaea62/bazel-sandbox/8022878262056817734/execroot/__main__/bazel-out/k8-fastbuild/bin/hack/verify_boilerplate.runfiles/__main__/kettle/monitor.py
becomes
kettle/monitor.py

krzyzacy/test-infra,kargakis/test-infra,michelle192837/test-infra,jessfraz/test-infra,foxish/test-infra,cjwagner/test-infra,kubernetes/test-infra,dims/test-infra,fejta/test-infra,kubernetes/test-infra,ixdy/kubernetes-test-infra,cjwagner/test-infra,kubernetes/test-infra,fejta/test-infra,ixdy/kubernetes-test-infra,jessfraz/test-infra,foxish/test-infra,fejta/test-infra,kargakis/test-infra,jlowdermilk/test-infra,jessfraz/test-infra,ixdy/kubernetes-test-infra,mindprince/test-infra,lavalamp/test-infra,jessfraz/test-infra,lavalamp/test-infra,abgworrall/test-infra,dims/test-infra,brahmaroutu/test-infra,michelle192837/test-infra,jessfraz/test-infra,shyamjvs/test-infra,cjwagner/test-infra,foxish/test-infra,monopole/test-infra,krzyzacy/test-infra,pwittrock/test-infra,mindprince/test-infra,foxish/test-infra,michelle192837/test-infra,jlowdermilk/test-infra,cblecker/test-infra,pwittrock/test-infra,dims/test-infra,cjwagner/test-infra,cblecker/test-infra,shyamjvs/test-infra,fejta/test-infra,cjwagner/test-infra,fejta/test-infra,kubernetes/test-infra,pwittrock/test-infra,ixdy/kubernetes-test-infra,lavalamp/test-infra,cblecker/test-infra,mindprince/test-infra,monopole/test-infra,monopole/test-infra,krzyzacy/test-infra,lavalamp/test-infra,BenTheElder/test-infra,shyamjvs/test-infra,fejta/test-infra,lavalamp/test-infra,shyamjvs/test-infra,cblecker/test-infra,dims/test-infra,monopole/test-infra,abgworrall/test-infra,abgworrall/test-infra,brahmaroutu/test-infra,cblecker/test-infra,shyamjvs/test-infra,kubernetes/test-infra,mindprince/test-infra,mindprince/test-infra,michelle192837/test-infra,jessfraz/test-infra,lavalamp/test-infra,brahmaroutu/test-infra,kargakis/test-infra,foxish/test-infra,ixdy/kubernetes-test-infra,brahmaroutu/test-infra,BenTheElder/test-infra,abgworrall/test-infra,michelle192837/test-infra,BenTheElder/test-infra,jlowdermilk/test-infra,krzyzacy/test-infra,jlowdermilk/test-infra,dims/test-infra,monopole/test-infra,abgworrall/test-infra,michelle192837/test-infra,monopole/test-infra,BenTheElder/test-infra,BenTheElder/test-infra,dims/test-infra,kargakis/test-infra,krzyzacy/test-infra,brahmaroutu/test-infra,cblecker/test-infra,jlowdermilk/test-infra,cjwagner/test-infra,jlowdermilk/test-infra,shyamjvs/test-infra,BenTheElder/test-infra,pwittrock/test-infra,kargakis/test-infra,pwittrock/test-infra,kargakis/test-infra,kubernetes/test-infra,krzyzacy/test-infra,brahmaroutu/test-infra