Omit multipicturedraw tests for Valgrind_PreAbandonGpuContext bot.

Bug: skia:6575
Change-Id: Ie937962e6a4f2dd989efca8ad94d35ad058bc87c
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/20226
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
2 files changed