A way to turn off report in cypress after()

**Is your feature request related to a problem? Please describe.**
We have a few test that have close to 40 it blocks. With out coverage these test take about ~3-4 min to run, but with coverage the test can take up to 15 min. We're seeing these test fail on the report part. When testing out with the `report` in the after() gone, test is able to pass in the 15 min.

In our system, we already run `nyc report` after the test passes.

**Describe the solution you'd like**
Having a way to turn off generateReport in https://github.com/cypress-io/code-coverage/blob/master/support.js#L226.

Maybe having a flag like `--no-report`

**Describe alternatives you've considered**
I was able to test the changes out by deleting these lines and locally monkey patch and see the test with a lot of it blocks passing and are able to get code coverage reports.