Delete legacy MutableTextureState functions

Client CLs:
 - https://crrev.com/c/5247185
 - https://crrev.com/c/5225028
 - http://ag/25968340

Bug: b/293490566
Change-Id: I528e95998adbdf3931809196db311f2c4fd65f59
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/807836
Reviewed-by: Greg Daniel <egdaniel@google.com>
2 files changed