Tests: Clean up and automate repository for Swift object store test Docker image

[matej-g]

As a part of #4735 (comment), we have now forked https://github.com/thanos-community/docker-swift-onlyone-authv2-keystone which contains code to build a Docker image required for our Swift object store tests. However, we should improve on this, namely by:

1. Allowing issues on the repo, so we can track things in there (this is not turned on by default for forks)
2. Cleaning-up the repo (Remove docs / information which is not applicable)
3. Automating Docker image build + push for each change (right now it has to be done manually)

[stale]

Hello 👋 Looks like there was no activity on this issue for the last two months.
Do you mind updating us on the status? Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
If there will be no activity in the next two weeks, this issue will be closed (we can always reopen an issue if we need!). Alternatively, use remind command if you wish to be reminded at some point in future.

[matej-g]

Valid ☝️

[stale]

Hello 👋 Looks like there was no activity on this issue for the last two months.
Do you mind updating us on the status? Is this still reproducible or needed? If yes, just comment on this PR or push a commit. Thanks! 🤗
If there will be no activity in the next two weeks, this issue will be closed (we can always reopen an issue if we need!). Alternatively, use remind command if you wish to be reminded at some point in future.

[matej-g]

Still relevant and 🆘 help wanted

[deepto98]

Can I pick this up?

[matej-g]

Hi @deepto98 absolutely go for it!

[PlytonRexus]

Hi! Is this still relevant, @matej-g? Also, would this be done with GH actions or CircleCI? And the pushing registry would still be Quay, right?