ci: update ignore_pull_requests to only include release-able branches
ci: update ignore_pull_requests to only include release-able branches

Currently certain steps like `e2e-cli-node-10` and `snapshot_publish` are being run for PRs which are created via non forked repos. Such as renovate and users who create PRs directly from github via `Edit file`.

Example of such branch names are;

```
renovate/sass-loader
alan-agius4-testing-branch
```

geofffilippi/angular-cli,angular/angular-cli,Brocco/angular-cli,Brocco/angular-cli,ocombe/angular-cli,geofffilippi/angular-cli,catull/angular-cli,ocombe/angular-cli,angular/angular-cli,filipesilva/angular-cli,clydin/angular-cli,beeman/angular-cli,ocombe/angular-cli,beeman/angular-cli,filipesilva/angular-cli,filipesilva/angular-cli,clydin/angular-cli,ocombe/angular-cli,catull/angular-cli,Brocco/angular-cli,clydin/angular-cli,angular/angular-cli,catull/angular-cli,Brocco/angular-cli,catull/angular-cli,clydin/angular-cli,Brocco/angular-cli,geofffilippi/angular-cli,manekinekko/angular-cli,beeman/angular-cli,beeman/angular-cli,ocombe/angular-cli,angular/angular-cli,manekinekko/angular-cli,geofffilippi/angular-cli,filipesilva/angular-cli,manekinekko/angular-cli