Revert "Define a movable variant of SequenceChecker"

This reverts commit 797bd0afe38685b635179f0870fbc4b019d049b5.

Reason for revert: A lock detector downstream didn't like it.

Original change's description:
> Define a movable variant of SequenceChecker
>
> and use it to instrument the (movable/copyable) IceCandidateCollection
>
> Bug: None
> Change-Id: I055b13d3c8c94eff5e045df691df5c0c523886ed
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/409546
> Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#45716}

Bug: None
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Ic29d440e65c34c7034d87c8da7f39126376cb306
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/411781
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#45720}