Move AcceleratedDHTClient from being experimental

[BigLep]

Done Criteria

The AcceleratedDHTClient is no longer communicated as an experimental feature.

Why Important

At least as of 2023-03-07 we have had the config Experimental.AcceleratedDHTClient even though it has been used in production by larger operators for a year plus. Whether we're happy with everything about the feature and implementation or not, we treat it like a production feature. We have seen large operators who would have benefitted from it, but weren't even aware. We're going to drive more awareness about the functionality, but before doing so, should be making its status clear that it's functionality we support and recommend.

Notes

This issue shouldn't be a license to go do a bunch of code cleanup, but if there is some small improvements to make to improve the maintenance burden we certainly can.

#9419 should get completed as part of this.

[BigLep]

2023-05-16 maintainer conversation:

• Need to add an error message in some case
• Need a PR to config.md (this is coming in the PR for this issue)