Test (client/jetbrains) CI job failing with `gulp not found`

Created by: jhchabran

Investigating this build showed that this particular job doesn't work if the cache isn't available.

[node_modules] - 🚨 Cache restore is skipped because s3://(...)/sourcegraph/sourcegraph/cache-node_modules-3f21cee23df6eba8d19bc1da7c6176d16f8a859e.tar does not exist

Looking at the bucket holding the cache, we can see that that specific file was created after this particular job was run. And when @umpox retried the job, it was present, so it worked this time.

The other tests are all using yarn-run.sh or yarn-test.sh which addresses this particular problem.

➡️ Solution is probably to use one of these scripts.