feat(test-runner): more default workers for M1 (#12660)
feat(test-runner): more default workers for M1 (#12660)

New default is based on the very (unscientific) output of repeated a few
times:

```
$ for i in `seq 5 13`; do time npm run ctest -- --reporter=line --workers=$i 'page/*' 'selector*' 'channels*' 'resource-timing*'; done
```

microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright,microsoft/playwright