WASM: builds are timing out due to helix queue capacity

[safern]

The WASM queue we're using because it is the only queue with v8 available in it to be able to execute WASM tests, only has 6 machines, and as we've enabled more test projects it is not keeping up, so currently all jobs are timing out.

@MattGal is adding v8 to a queue with more capacity and that should be available on Wednesday's rollout. In the meantime we're going to disable running the browser tests in all PRs and will make it trigger only when we touch tests.proj which is how we've been enabling new test projects.

cc: @steveisok @akoeplinger @marek-safar @lewing

[Dotnet-GitSync-Bot]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

Tagging subscribers to this area: @safern, @ViktorHofer
Notify danmosemsft if you want to be subscribed.