chore(ci): split build and tests jobs in abi_wasm.yml

[TomAFrench]

Description

Problem*

Summary*

This separates the building and testing of noirc_abi_wasm which, among other things, allows easier rerunning in the case of a flakey test failure.

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[TomAFrench]

I've found the underlying cause for this issue.

When we were downloading the artifact, we were overwriting the package.json with the one from the build outputs. This had some fields filtered out of it which resulted in the yarn behaviour.

[TomAFrench]

Oof, requested review too soon.