Remove prerelease flag from all beta releases when promoting

[steffenkleinle]

Describe the Problem

Currently, only the latest prerelease flag of the latest github release of the current platform is removed during a promotion. Accordingly, there are quite a few releases which still have the prerelease flag set.
However, this is wrong, as also those releases (or whatever is included in those releases) is now on production.

Describe Your Preferred Solution

When promoting releases for a platform (android, ios, web) with github-promote-release, all releases corresponding to that platform should loose their prerelease flag.
Releases for other platforms should not be affected.

Describe Possible Alternatives

Keep it as it is.

Related Issues

❗ Check the status of integrating the app toolbelt, this will lead to conflicts: #2644
Related to/blocked by: #3069

Additional Information

N/A