Fix mac-swangle-chromium-try-x64 builder dimensions

Don't specify ssd dimension.

TBR=kbr

Bug: 1064477
Change-Id: Idd00b8601bbfd072bf4043ee27c9beebeb56c915
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2136270Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756467}

infra/config/generated/cr-buildbucket.cfg

@@ -19636,7 +19636,6 @@ buckets: <
       dimensions: "cpu:x86-64"
       dimensions: "os:Mac"
       dimensions: "pool:luci.chromium.swangle.chromium.mac.x64.try"
-      dimensions: "ssd:0"
       recipe: <
         name: "chromium_trybot"
         cipd_package: "infra/recipe_bundles/chromium.googlesource.com/chromium/tools/build"

infra/config/lib/try.star

@@ -224,6 +224,7 @@ def chromium_swangle_mac_builder(*, name, **kwargs):
   return chromium_swangle_builder(
       name = name,
       cores = None,
+      ssd = None,
       goma_backend = builders.goma.backend.RBE_PROD,
       os = builders.os.MAC_ANY,
       **kwargs