Fix the exclude regexp for the infra config directory.

Change-Id: I9e3b5d5d30090fbcf3ab40933541ebb81350ce2f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2350241
Auto-Submit: Garrett Beaty <gbeaty@chromium.org>
Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797037}

infra/config/lib/try.star

@@ -22,7 +22,7 @@ load("@stdlib//internal/luci/common.star", "keys")
 load("./builders.star", "builders")
 load("./args.star", "args")
 
-INFRA_CONFIG_LOCATION_REGEXP = "infra/config/.+"
+INFRA_CONFIG_LOCATION_REGEXP = ".+/[+]/infra/config/.+"
 
 defaults = args.defaults(
     extends = builders.defaults,