Clean up use of IDWriteFontFace5

Back in 2018 IDWriteFontFace5 was new and use needed to be behind build
flags since not every user had the newest headers. However,
IDWriteFontFace5 has been used elsewhere directly since 2020. Remove the
no longer needed extra build flags and clean up use.

Change-Id: I1dac92e878a41b36708dcf77ca3a68f0b7279fc4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1161556
Reviewed-by: Florin Malita <fmalita@google.com>
Reviewed-by: Julia Lavrova <jlavrova@google.com>