Blacklist gpu_blur_utils GMs from gltestthreading

Change-Id: Ibefd9c8886f23073dcf5c70d8dfd49cc5e244bc3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/289996
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
2 files changed