Revert "IWYU stats related files"

This reverts commit 48f271fba90d4a6d8699e813cd049014de502523.

Reason for revert: Breaks downstream tests

Original change's description:
> IWYU stats related files
>
> caused Chromium compile failures:
>   https://chromium-review.googlesource.com/c/chromium/src/+/6289230
>
> BUG=webrtc:42226242
>
> Change-Id: I6a5179638e23bf94326b3f8948a167c20f66591a
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/378180
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Philipp Hancke <phancke@meta.com>
> Reviewed-by: Henrik Boström <hbos@webrtc.org>
> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#43989}

Bug: webrtc:42226242
Change-Id: I3e7458e0ae354dd58bbf704902e78500e94f5ae3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/379000
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43997}