Add "pool" to swarming dimesions

NOTRY=true

Bug: chromium:1126457
Change-Id: I5239fe552e71d7a9a20a07188a368fd57429142a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2404449
Commit-Queue: Almothana Athamneh <almuthanna@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69848}

infra/testing/PRESUBMIT.py

@@ -30,6 +30,7 @@ SUPPORTED_SWARMING_DIMENSIONS = [
   'device_os',
   'device_type',
   'os',
+  'pool',
 ]
 
 # This is not an exhaustive list. It only reflects what we currently use. If