Backport #40994 and #41280: Add support in signing scripts to sign release for some archs only & Update download-android-*.json files for android-only releases

Backport Patchset

Book-keeping

Gitlab Issue(s)

• #40994 (closed)
• #41280 (closed)

Merge Request(s)

• !1210 (merged)

Target Channels

• maint-14.5
• maint-13.5

Notes

We should backport this after it has been tested signing an alpha release.