Revert "cr-buildbucket.cfg: Add cache for win_toolchain"

We already had these caches set up and luci-config now complains about
duplicate keys.

This reverts commit 484aca1d1f2645a413e4e985c0ccc76f7ae167ad.
diff --git a/infra/config/global/cr-buildbucket.cfg b/infra/config/global/cr-buildbucket.cfg
index b1f4d75..5846e13 100644
--- a/infra/config/global/cr-buildbucket.cfg
+++ b/infra/config/global/cr-buildbucket.cfg
@@ -91,10 +91,6 @@
         name: "dawn"
       }
       service_account: "dawn-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
-      caches {
-        path: "win_toolchain"
-        name: "win_toolchain"
-      }
     }
 
     # Linux: test combinations of {clang}x{release,debug}x{x86,x64}
@@ -202,10 +198,6 @@
         properties_j: "$depot_tools/bot_update:{\"apply_patch_on_gclient\":true}"
       }
       service_account: "dawn-try-builder@chops-service-accounts.iam.gserviceaccount.com"
-      caches {
-        path: "win_toolchain"
-        name: "win_toolchain"
-      }
     }
 
     # A subset of the CI configurations are used for the CQ. We still mirror