remove unused (by clients) SkMultiPictureDraw

More cleaning to do if we like this idea...

Change-Id: I608143db085911565dd5f5426f7ee6436ec58cdf
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/254680
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
15 files changed