Reduce the core count on the Windows GPU FYI builders to 8.

This matches the previous bots.

BUG=811828
BUG=811794
BUG=811791
BUG=811823
BUG=811871
BUG=811830
BUG=812108
BUG=811867
BUG=811817
BUG=811800
BUG=811826
BUG=811833
BUG=811805
BUG=811824
BUG=811793
BUG=811868
BUG=811783
BUG=811818
BUG=811788
BUG=811784

TBR=jbudorick@chormium.org

Change-Id: I665422d47731ab4a5379395be60f63a1dc92881f
Reviewed-on: https://chromium-review.googlesource.com/957204Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542168}

infra/config/global/cr-buildbucket.cfg

@@ -617,37 +617,37 @@ buckets {
     builders {
       name: "GPU FYI Win Builder"
       mixins: "win-gpu-fyi-ci"
-      dimensions: "cores:32"
+      dimensions: "cores:8"
     }
     builders {
       name: "GPU FYI Win Builder (dbg)"
       mixins: "win-gpu-fyi-ci"
-      dimensions: "cores:32"
+      dimensions: "cores:8"
     }
     builders {
       name: "GPU FYI Win Clang Builder (dbg)"
       mixins: "win-gpu-fyi-ci"
-      dimensions: "cores:32"
+      dimensions: "cores:8"
     }
     builders {
       name: "GPU FYI Win dEQP Builder"
       mixins: "win-gpu-fyi-ci"
-      dimensions: "cores:32"
+      dimensions: "cores:8"
     }
     builders {
       name: "GPU FYI Win x64 Builder"
       mixins: "win-gpu-fyi-ci"
-      dimensions: "cores:32"
+      dimensions: "cores:8"
     }
     builders {
       name: "GPU FYI Win x64 Builder (dbg)"
       mixins: "win-gpu-fyi-ci"
-      dimensions: "cores:32"
+      dimensions: "cores:8"
     }
     builders {
       name: "GPU FYI Win x64 dEQP Builder"
       mixins: "win-gpu-fyi-ci"
-      dimensions: "cores:32"
+      dimensions: "cores:8"
     }
     builders {
       name: "Win10 FYI Debug (NVIDIA)"