chore(download): when content size does not match, use unlinkSync

[cnishina]

Switch unlink in favor of unlinkSync...

https://github.com/angular/webdriver-manager/blob/master/lib/files/downloader.ts#L158

[cnishina]

Another place to switch unlink in favor of unlinkSync:

https://github.com/angular/webdriver-manager/blob/master/lib/files/downloader.ts#L144

Also https://github.com/angular/webdriver-manager/blob/master/lib/files/downloader.ts#L141 looks like it pipes the file. To just make sure we have better error handling....Does the pipe only happen if the file is downloaded? How is the error case handled from the request and are we missing any events to catch errors for file.on?

[cnishina]

closed with 236a8ec.