Follow up to #64, based on discussion in #64 (comment):

Actually you don't use any "install" API like the one that is used in integration tests of package-registry. It looks like it's not required to be involved in the process, so I wonder what does it do actually? ... I was thinking about the reference to this API method: https://github.com/elastic/package-storage/blob/production/testing/main_integration_test.go#L108

Hmmm, good question — I wonder how I'm able to get things working even without calling this API. 🤔 Let's leave it out of this PR for now and add it if we need it in a follow up PR.