win/asan bot: Remove cores:32 dimension.

Looks like my new bot is only found without this requirement:

https://chromium-swarm.appspot.com/botlist?c=id&c=os&c=task&c=status&f=cores%3A32&f=builder%3Awin-asan&f=os%3AWindows-10&f=cpu%3Ax86-64&f=pool%3Aluci.chromium.ci&l=100&s=id%3Aasc

https://chromium-swarm.appspot.com/botlist?c=id&c=os&c=task&c=status&f=builder%3Awin-asan&f=os%3AWindows-10&f=cpu%3Ax86-64&f=pool%3Aluci.chromium.ci&l=100&s=id%3Aasc

Bug: 869973,871764
Change-Id: I9f6f6e8bdfb0f62553266ad9eac4a12fcfdedd9f
Reviewed-on: https://chromium-review.googlesource.com/1171023Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582212}

infra/config/global/cr-buildbucket.cfg

@@ -1301,7 +1301,6 @@ buckets {
     builders {
       name: "win-asan"
       dimensions: "os:Windows-10"
-      dimensions: "cores:32"
       mixins: "memory-ci"
     }
     builders {