Blacklist more flaky GMs in gltestthreading config

Bug: skia:7011 skia:6544
Change-Id: Idacb5ff8090bea6ddbdef710bc0f4dbb8bd23549
Reviewed-on: https://skia-review.googlesource.com/43560
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
5 files changed