Revert of Make SkGpuBlurUtils::GaussianBlur more drawContext centric (patchset #2 id:20001 of https://codereview.chromium.org/1962903003/ )

Reason for revert:
This looks to be causing errors in Gold.  I don't know if I can make a permanent link to something in Gold, but take a look at imagefilterscropexpand for an example.

Original issue's description:
> Make SkGpuBlurUtils::GaussianBlur more drawContext centric
>
> This is split out of https://codereview.chromium.org/1959493002/ (Retract GrRenderTarget from SkGpuBlurUtils)
>
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1962903003
>
> Committed: https://skia.googlesource.com/skia/+/e7ef01dcfda0f8ae407ba92cc03cf3f7841ec470

TBR=bsalomon@google.com,robertphillips@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/1973563002
4 files changed