ci: remove `cla: yes` from required labels
ci: remove `cla: yes` from required labels

Remove `cla: yes` from the require labels for merging as the CLACheck
tool no longer relies on labels.

Enforcement of the CLA being signed is still enforced by the status check
which is visible both in Github as well as checked by merge tooling.

clydin/angular-cli,catull/angular-cli,geofffilippi/angular-cli,clydin/angular-cli,geofffilippi/angular-cli,catull/angular-cli,Brocco/angular-cli,Brocco/angular-cli,Brocco/angular-cli,geofffilippi/angular-cli,angular/angular-cli,angular/angular-cli,Brocco/angular-cli,angular/angular-cli,geofffilippi/angular-cli,angular/angular-cli,clydin/angular-cli,catull/angular-cli,clydin/angular-cli,Brocco/angular-cli,catull/angular-cli