Do `npm run test:prepare` in separate GHA step

[jennydaman]

This might help with timing and avoiding timeouts when running tests in GitHub Actions.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 32.82%. Comparing base (dac03ce) to head (07e114a). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1240 +/- ## ======================================= Coverage 32.82% 32.82% ======================================= Files 194 194 Lines 6400 6400 Branches 1330 1330 ======================================= Hits 2101 2101 Misses 4171 4171 Partials 128 128 ``` | [Flag](https://app.codecov.io/gh/FNNDSC/ChRIS_ui/pull/1240/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FNNDSC) | Coverage Δ | | |---|---|---| | [e2etests-local](https://app.codecov.io/gh/FNNDSC/ChRIS_ui/pull/1240/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FNNDSC) | `27.07% <ø> (ø)` | | | [e2etests-public](https://app.codecov.io/gh/FNNDSC/ChRIS_ui/pull/1240/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FNNDSC) | `27.67% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FNNDSC#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[PintoGideon]

Oh nice. 👍🏽