Remove reference to nonexistent v1 dev UI from quickstart

[holly-cummins]

While I was looking at the index html, I noticed it's out of date in a few other ways (references to reactive, etc) so I've tidied those up as well.

[phillip-kruger]

If this is using a later version of Quarkus, you can just remove the index file, as it's dynamic now

[quarkus-bot]

Status for workflow Pull Request Build - development

This is the status report for running Pull Request Build - development on commit 76fbbe0.

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It should be safe to merge provided you have a look at the other checks in the summary.

[holly-cummins]

If this is using a later version of Quarkus, you can just remove the index file, as it's dynamic now

I realised we do it dynamically after I'd made the changes, but didn't think about the implications for this quickstart. I guess in the development branch it definitely will be a later version of Quarkus, and the less code we have the better, so good idea, I'll remove it. Thanks.

[holly-cummins]

Actually, should we remove the index.htmls for all quickstarts in this repository?

[phillip-kruger]

Yes I think we can remove it from all quickstarts (if they use the latest Quarkus)

[holly-cummins]

Closing in favour of #1459.