removed option to specify github teams for "needs-sig" label (#15399)
removed option to specify github teams for "needs-sig" label (#15399)

* removed option to specify github teams for "needs-sig" label

when needs-sig label is applied, two options are available. The first option, github teams need to be specified and for the second one, sig label needs to be specified manually. This PR removes the option of adding github teams(option 1) from the usage of needs-sig label.

* this removes team from being mentioned and only suggests to add a label when no sig labels are not added on an issue

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