fix: exit with error on retry give up

When browser not responding karma just logs `ERROR [launcher]: <browser> failed 2 times (timeout). Giving up.` and hangs.

We should exit with error in such case.
Why don't we get into this place when [self.retryLimit equal 0](https://github.com/karma-runner/karma/pull/1151/files#diff-8f1f2530ff87562023072db028da6b88R20)?