Revert "CoreText SkTypeface palette support"

This reverts commit 36c3b381b1772318063cef2ecb424e29ea3ea2b9.

Bug: https://github.com/flutter/flutter/issues/158423
Change-Id: If604627553be1e463b213ec6b646ba5f22cc7748
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/918416
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
(cherry picked from commit ac75382cb971d2f5465b4608a74561ecb68599c5)
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/919136