9.x -> 10.x: Increase in Origin Connection Counts

[bneradt]

While testing ATS 10 in production, I noticed that we had about 3 times the connection counts to the origin than we had in peer ATS 9.x hosts within the same colo. ss corroborated the connection counts so it wasn't metrics issue. Doing a binary search on commits, I noticed that the increased count was correlated with #9872. Locally we'll work around the issue by simply backing out #9872, #10104, and #10106 which gets us back to the ts IntrusiveHashMap rather than the libswoc one.

@SolidWallOfCode and I have discussed this. There will likely be a libswoc update to address the issue.

[traeak]

Related to #9689

I found some performance regressions while working on #10897 I'll probably add those changes there. The primary one is with swoc::IntrusiveHashMap, a much smaller one with switch over to Metrics:: (easy to resolve). Looking for the remaining ones.