Remove SK_DISABLE_LEGACY_VK_GRDIRECTCONTEXT_FACTORIES

Client CLs:
 - cr/573240675
 - https://crrev.com/c/4935441
 - http://ag/25042956
 - http://ag/25042955
 - https://github.com/flutter/engine/pull/46878

Change-Id: Ic0ed846502be5fa9bc29408d213a85cd7879b08a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/781196
Owners-Override: Kevin Lubick <kjlubick@google.com>
Auto-Submit: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
2 files changed