milo: Fix shortname label for blink heap verification.

Change-Id: Iab7d8a85f5b4ee0bbbf98e72bc69cb6666ed7b6c
Reviewed-on: https://chromium-review.googlesource.com/954602Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Benjamin Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541844}

infra/config/global/luci-milo.cfg

@@ -2668,7 +2668,7 @@ consoles: {
   builders: {
     name: "buildbucket/luci.chromium.ci/linux-blink-heap-verification"
     category: "linux|blink"
-    short_name: "IM"
+    short_name: "VF"
   }
   builders: {
     name: "buildbot/chromium.fyi/Linux ARM"