Revert of SkPDF: PDF/A runtime switch (patchset #1 id:100001 of https://codereview...

Revert of SkPDF: PDF/A runtime switch (patchset #1 id:100001 of https://codereview.chromium.org/1891873002/ )

Reason for revert:
breaking something.

Original issue's description:
> SkPDF: PDF/A runtime switch
>
> TODO: remove gyp variable and modify API  in SkDocument.h
>
> BUG=skia:3110
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1891873002
>
> Committed: https://skia.googlesource.com/skia/+/570f18b43417d73c3fbd113cc0b4258e08b14c82

TBR=tomhudson@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:3110

Review URL: https://codereview.chromium.org/1892203002