tests: remove flaky Chrome launch from unit-cli

[brendankenny]

In the spirit of improving flaky tests, unit-cli has loooong had a flake based on a Chrome launch sometimes timing out. You know the one:

●  process.exit called with "1"

      84 | function printConnectionErrorAndExit() {
      85 |   console.error('Unable to connect to Chrome');
    > 86 |   return process.exit(_RUNTIME_ERROR_CODE);
         |                  ^
      87 | }
      88 | 
      89 | /** @return {never} */

      at printConnectionErrorAndExit (lighthouse-cli/run.js:86:18)

(for example: https://github.com/GoogleChrome/lighthouse/runs/2249363555?check_suite_focus=true)

The issue is that this is more or less a smoke test without any of the functionality we've built into smokehouse to handle dealing with launching and testing with Chrome in a CI environment.

Looking way back, the original point of the test (from #2602) was to make sure that Lighthouse can run when lighthouse-cli is accessed directly as a node module, since our smoke tests load Lighthouse via CLI. Very similar to the smoke tests, but we have no other test ensuring we don't break this particular use case. Since then, the assertions have grown to check a few other aspects of the run.

However the overlap between this and smokehouse's execution path is almost total (they both pass through runLighthouse in run.js), so it seems sufficient for this test to run lighthouse with --auditMode and the sample artifacts to make sure it's runnable, and trust smokehouse to verify run.js is exercising the gathering steps.

After this I believe there's no other Chrome launch in unit-cli, so it should be stable going forward.

[connorjclark]

want to also revert the run: yarn unit-cli || yarn unit-cli --onlyFailures bit?

[patrickhulce]

so glad to see this flake gone for good :)

[brendankenny]

want to also revert the run: yarn unit-cli || yarn unit-cli --onlyFailures bit?

I like that confidence :) We can see how it goes