Revert "Split Equal weighted buttons metric on sync screen by source."

This reverts commit 4139bcb437268a5cf830a5a00b056038bd2d3bae.

Reason for revert: b/342000859

Original change's description:
> Split Equal weighted buttons metric on sync screen by source.
>
> all times.
>
> Minor: fixed metric for "settings" case; this button remains visible at
> Bug: b/318349306
> Change-Id: I21958d3c0cb34e25630078988abcae3604ee5d8c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5540604
> Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
> Commit-Queue: Tomek Jurkiewicz <tju@google.com>
> Reviewed-by: Alex Ilin <alexilin@chromium.org>
> Reviewed-by: Tanmoy Mollik <triploblastic@google.com>
> Cr-Commit-Position: refs/heads/main@{#1303676}

Bug: b/318349306
Change-Id: I5186a8c6eb0d58f3460729a5a26c785e904b2ca2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5555886
Auto-Submit: Sinan Sahin <sinansahin@google.com>
Owners-Override: Sinan Sahin <sinansahin@google.com>
Commit-Queue: Sinan Sahin <sinansahin@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1304049}