Remove superfluous weak_ptr.h includes from headers

Mostly automated with the following command:

git ls-files | grep '\.h$' | xargs grep -l base/memory/weak_ptr.h | \
  xargs grep -L WeakPtr | \
  xargs tools/add_header.py --header '"base/memory/weak_ptr.h"' --remove

Bug: 40318405
Change-Id: I1f4fff529f8b031a39f1726c5267f45aec541185
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7097925
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Owners-Override: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1539773}
NOKEYCHECK=True
GitOrigin-RevId: f343f46c12dce1a94642a70d328fc9f01b0abc9c