Previously, the `dev` npm script in `aio/aio-builds-setup/scripts-js/`
(the PR preview server implementation) would run both linting and unit
tests. This was slow and delayed the feedback loop on each change.
Since the `dev` script should be run during development and give
feedback as fast as possible, this commit removes the linting from the
`dev` script and only keeps the unit tests. Linting is still run in the
`test` npm script (which is more comprehensive). Also, in most cases the
developer's IDE will show linting errors in real time in the editor.
PR Close#36837