action #153427
## Motivation
In #153145 we saw that the `dist/rpm/update-cache.sh` script does not work in the case when we add new assets or change urls for existing assets.
If you make a pull request with a new url, then it will fail in OBS because it has the old cache.
But running update-cache.sh will use the upstream openQA git repo which has the old url.
So it's a chicken-egg problem.
That also is related to when others try to build openQA outside the context of OBS, see recent discussions in https://app.element.io/#/room/#openqa:opensuse.org
## Acceptance criteria
* **AC1:** It is not necessary to manually update the cached assets for rpm packaging when a remotly fetched asset is changed (in `assetpack.def`)
## Suggestions
* Read and review http://open.qa/docs/#update-asset-cache
* Research or ask other users of OBS for best practices of caching external assets as OBS can not directly download external packages
* Consider using OBS services to download/update assets
* https://github.com/openSUSE/obs-service-download_files ?
* The cockpit package requires a ton of npm packages to be bundled, maybe a good example (https://build.opensuse.org/package/show/openSUSE:Factory/cockpit)
* Try it out with changing/adding assets like a new javascript module pulled in in a temporary draft PR, e.g. jquery upgrade?
* If we'd use webpack we could reuse the approach taken by cockpit packaging. Revisit #71476