Separate out test case generation from deployment

Rather than looping over branches (in included template from `pages`),
generate the test cases here, provide these as an artifact and deploy
in a separate job. This avoids the regeneration of pages that have
not changed.

Use the apertis-test-cases-web as part of a multi-project pipeline to
deploy. Remove the deployment tools from this branch.

Whilst we are here, utilise an environment variable for the release to
make it easier to migrate this between releases.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>