tests(devtools): remove webtests, sync e2e tests, use release mode

[connorjclark]

We can remove these tests now, because we're starting to migrate to e2e tests (#14110). Pretty sure the devtools smoke tests will cover things just as well in the interim, but we can consider 10.0 blocking on the e2e migration.

• Removes webtests CI job and associated files
• Move all of chromium-web-tests to devtools-tests
• Except for blink_tools and content_shell, no longer need that

[adamraine]

Some version of https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3721466 will fix the problem, and we already made these tests optional for merging PRs. Is there an urgent reason to remove these tests?

[connorjclark]

We're committed to dropping these tests, have already started porting a couple, and won't do another CDT release before that process finishes. No need to continue playing the whack-a-mole game anymore. They'll still be in the CDT frontend for now, in case they catch something important.

[adamraine]

They'll still be in the CDT frontend for now, in case they catch something important.

I'm not so sure, it seems like our web tests are non-fatal in DT frontend. They didn't catch the issue in https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3721466 before it happened. I guess that makes us the only place the tests "matter"?

Since we're not doing another release until it's done I'm fine with merging this, but it seems like https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3721466 could buy us a few more weeks of use instead of creating a blind spot in our tests for a few weeks.