CI - speed up invenio-cli install step

[cc-a]

The CI workflow currently runs invenio-cli install in preparation for running the test suite. That command does a number of things not all of which may be required for our current level of testing. In particular it builds the javascript assets which I don't think are required unless we start building any front-end tests. Suggest figuring out what steps invenio-cli install is doing and figuring out which ones can be skipped. Our Dockerfile should give a good indication of the actual setup steps that are being run.