Workflow bug fixes

jq is already installed on ubuntu runner, so no need to query apt and install
Fix the cache keys - when the workflow was split I did not update the hashfile of the workflow
Remove the workaround for the fail-on-cache-miss bug now that it has been fixed upstream
Remove the unnecessary debug printing of lists in the clear-oolite-caches job
Add comments to better document the workflows
Make the cron job check Oolite's master branch for commits, rather than to the whole repository

Bzomak / oolite-msys2