Disable PinnedImageTest on Test-Win10-MSVC-AlphaR2-GPU-RadeonR9M470X-x86_64-Release-ANGLE bot

Bug: skia:7096
Change-Id: I536d81110c842da662b32a94a352a34a6854e3a9
Reviewed-on: https://skia-review.googlesource.com/55140
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
3 files changed