fix(sync-release): upload to lookaside cache only for Fedora

[mfocko]

When uploading the sources to lookaside cache, we cannot upload them to the CentOS as the cache is writeable only on the VPN / internal network.

However we still want to be able to submit updates via an MR, even if maintainer has to submit the archives to the lookaside cache by themselves.

Once the workflow with regards to the lookaside cache has been improved, drop this requirement from our side.

TODO:

• [x] Write new tests or update the old ones to cover new functionality.
• [x] Update doc-strings where appropriate.
• [x] Update or write new documentation in packit/packit.dev.

(no release notes… disabling something that didn't even work in the first place…)

[softwarefactory-project-zuul[bot]]

Build failed. https://softwarefactory-project.io/zuul/t/packit-service/buildset/425692b700384634b631fa52165bfa00

:heavy_check_mark: pre-commit SUCCESS in 2m 30s :x: packit-service-tests FAILURE in 2m 27s

[softwarefactory-project-zuul[bot]]

Build succeeded. https://softwarefactory-project.io/zuul/t/packit-service/buildset/cc604e835ba040f2913c6674d3296bc7

:heavy_check_mark: pre-commit SUCCESS in 2m 48s :heavy_check_mark: packit-service-tests SUCCESS in 2m 35s

[softwarefactory-project-zuul[bot]]

This change is unable to merge due to a missing merge requirement.

[mfocko]

This change is unable to merge due to a missing merge requirement.

Didn't know Zuul is smart enough to check for the GitHub requirements too :eyes:

[softwarefactory-project-zuul[bot]]

Build succeeded (gate pipeline). https://softwarefactory-project.io/zuul/t/packit-service/buildset/85f88829c05947e08c6e451571388941

:heavy_check_mark: pre-commit SUCCESS in 3m 03s