This is my concern as well. Unfortunately Xcode cloud doesn't support git, it supports a handful of specific git vendors (Git, Bitbucket), so it's not currently an option for my team. 7 or 8 years ago, I updated some software that broke Xcode server on our team's CI/CD. This was the one and only time in 15 years of building Apple software that I posted the issue on Apple Developer Forums, and within about an hour, I had a response from the engineering team, and over the course of the evening they deployed changes to their systems that fixed the issue on the spot (fortunately, it was something that could be fixed in that way, this seems like it could require an update or specific steps to fix). This issue doesn't appear to be resonating, which is a disappointment. It looks like Xcode 13/Montery works for a few people, but my guess would be that they didn't test it much or at all, and I'm not optimistic they will be motivated to get it fixed.

Having the same problem; I suspect circumstances have changed from when the OP's question and the cached keychain answer was proposed. I wonder if it extends from Xcode 13 and Monterey, I'm trying to enable Xcode server on a freshly-wiped Mac and can't get past this SSL configuration error.