Replace if () NOTREACHED() with CHECK() in base/apple

Replace simple cases of if (foo) NOTREACHED(); and if (!bar)
NOTREACHED() with CHECK(!foo); and CHECK(bar) in
base/apple.

This aligns with current guidance:
https://chromium.googlesource.com/chromium/src/+/main/styleguide/c++/checks.md#:~:text=Use%20CHECK(bar)%3B%20instead

Most changes were automated with regular expression substitutions.

This CL was uploaded by git cl split.

R=mark@chromium.org

Change-Id: Icc15ec2eff988b9d72b9c36c6f603be7c2906bdc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5822812
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
Auto-Submit: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1350221}