Add 'schedule' event name in configure_ci.py (#12514)

This is currently breaking all nightly workflows.

build_tools/github_actions/configure_ci.py

diff --git a/build_tools/github_actions/configure_ci.py b/build_tools/github_actions/configure_ci.py
index 2b7a834..49ac80d 100755
--- a/build_tools/github_actions/configure_ci.py
+++ b/build_tools/github_actions/configure_ci.py
@@ -36,6 +36,7 @@
 
 PULL_REQUEST_EVENT_NAME = "pull_request"
 PUSH_EVENT_NAME = "push"
+SCHEDULE_EVENT_NAME = "schedule"
 WORKFLOW_DISPATCH_EVENT_NAME = "workflow_dispatch"
 SKIP_CI_KEY = "skip-ci"
 RUNNER_ENV_KEY = "runner-env"
@@ -208,6 +209,8 @@
     return "presubmit"
   elif event_name == PUSH_EVENT_NAME:
     return "postsubmit"
+  elif event_name == SCHEDULE_EVENT_NAME:
+    return "postsubmit"
   elif event_name == WORKFLOW_DISPATCH_EVENT_NAME:
     return "unknown"
   raise ValueError(f"Unrecognized event name '{event_name}'")