[Proposal] Disable Beta builds temporarily

[RealVishy]

I don't see any big experimental PRs we might need it for, and it'll save us builder time for now.
Only thing i'm not sure about is if it'll auto migrate users to other channels.

[p5]

We do not auto migrate users over, though made it clear that these will be turned off in the near future, and for people to rebase to F41 when it's released.

I don't believe we announced these images or shared them publicly, so there shouldn't be many/any users.

[castrojo]

4 pulls with the last build, probably noise:

https://github.com/ublue-os/bluefin/pkgs/container/aurora/328985424?tag=beta

[ledif]

Agreed. I just disabled the workflow.

These instructions are from @castrojo on Discord. I'll post them here for reference in case we need to enable them again

https://github.com/ublue-os/aurora/actions/workflows/build-image-beta.yml
this will turn off beta builds, you don't need to PR anything