chromium.goma: fix category for Chromium Android ARM 32-bit Goma RBE Staging

Change-Id: If78728aac86b3108e6525cffcee0dfc6122db607
Reviewed-on: https://chromium-review.googlesource.com/c/1312180Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Shinya Kawanaka <shinyak@chromium.org>
Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Commit-Queue: Fumitoshi Ukai <ukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604804}

infra/config/global/luci-milo.cfg

@@ -3217,8 +3217,7 @@ consoles {
   }
   builders {
     name: "buildbucket/luci.chromium.ci/Chromium Android ARM 32-bit Goma RBE Staging"
-    category: "rbe|rel|android"
-    short_name: "arm"
+    category: "rbe|android arm|rel"
   }
 }