Fix infra watchlist spec.

I don't want to be CCed on everything.

Change-Id: I14d2af4906be4626827c7cbca7ee59fbe86a8420
Reviewed-on: https://chromium-review.googlesource.com/c/1305633
Commit-Queue: John Budorick <jbudorick@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603557}

WATCHLISTS

@@ -1000,7 +1000,7 @@
     'infra': {
       'filepath': 'infra/config|'\
                   'testing/buildbot|'\
-                  'tools/mb|',
+                  'tools/mb',
     },
     'ink_drop': {
       'filepath': 'ui/views/animation/test/.*ink_drop.*|' \