Revert "UPSTREAM: unicode: Don't special case ignorable code points"

This reverts commit 62bbb08add179b68e2ce0ede59f3c4b37d6c92a8.

Reason for revert: b/382800956

Bug: 382800956
Change-Id: Ic7a0cdbb060c12c1628a5859d795e78cd6b9341d
Signed-off-by: Todd Kjos <tkjos@google.com>
(cherry picked from commit c376628415656f16d398aad95c218a06805038bd)
Signed-off-by: Lee Jones <joneslee@google.com>