Add path regex handling to luci sched generation, use for infra/config.

Add the ability for chromeos_config.py to specify path_regexps for
triggers and use them for luci-scheduler-updater triggering on the
infra/config repo.

BUG=None
TEST=cros_sdk -- /mnt/host/source/chromite/config/refresh_generated_files
TEST=./run_tests

Change-Id: I0a5009e878636e25ef8b209ba18512cadf3aba92
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2265200
Commit-Queue: David Burger <dburger@chromium.org>
Tested-by: David Burger <dburger@chromium.org>
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
Reviewed-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
diff --git a/scripts/gen_luci_scheduler_unittest.py b/scripts/gen_luci_scheduler_unittest.py
index f54998c..1f543b3 100644
--- a/scripts/gen_luci_scheduler_unittest.py
+++ b/scripts/gen_luci_scheduler_unittest.py
@@ -64,6 +64,7 @@
     trigger_name = 'simple'
     repo = 'url://repo'
     refs = ['refs/path']
+    path_regexps = ['path/regexps']
     builds = ['test_build']
 
     expected = """
@@ -74,13 +75,14 @@
   gitiles: {
     repo: "url://repo"
     refs: "refs/path"
+    path_regexps: "path/regexps"
   }
   triggers: "test_build"
 }
 """
 
     result = gen_luci_scheduler.genSchedulerTrigger(
-        trigger_name, repo, refs, builds)
+        trigger_name, repo, refs, path_regexps, builds)
 
     self.assertEqual(result, expected)
 
@@ -107,7 +109,7 @@
 """
 
     result = gen_luci_scheduler.genSchedulerTrigger(
-        trigger_name, repo, refs, builds)
+        trigger_name, repo, refs, None, builds)
 
     self.assertEqual(result, expected)