Suppress warnings for LTS builds

They aren't in use in any console but are still checked for by the hooks

BUG: chromium:1127088
Change-Id: Ibd13b00cfa23b56a3245035bf5b86533705112bd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2527942
Auto-Submit: Jacob Kopczynski <jkop@chromium.org>
Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825532}

testing/buildbot/generate_buildbot_json.py

@@ -1439,6 +1439,13 @@ class BBJSONGenerator(object):
         'win32-dbg',
         'win-archive-dbg',
         'win32-archive-dbg',
+        # TODO(https://crbug.com/1127088): remove once LTS version has been set
+        "chromeos-arm-generic-lts",
+        "chromeos-betty-pi-arc-chrome-lts",
+        "chromeos-eve-chrome-lts",
+        "chromeos-kevin-chrome-lts",
+        "linux-chromeos-lts",
+        "linux64-lts",
     ]
 
   def get_internal_waterfalls(self):