Update bots to pull main instead of master

Bug: 183190456
Change-Id: Id8f83b814b401353cb4e413f5437003d8ab6047d
diff --git a/infra/config/global/luci-scheduler.cfg b/infra/config/global/luci-scheduler.cfg
index 5e0355e..b782dbe 100644
--- a/infra/config/global/luci-scheduler.cfg
+++ b/infra/config/global/luci-scheduler.cfg
@@ -19,11 +19,11 @@
 # The format of this file is important, we have a hackish parsing to trigger
 # builds in tools/trigger.py
 trigger {
-  id: "master-gitiles-trigger"
+  id: "main-gitiles-trigger"
   acl_sets: "default"
   gitiles: {
     repo: "https://r8.googlesource.com/r8"
-    refs: "refs/heads/master"
+    refs: "refs/heads/main"
   }
   triggers: "archive"
   triggers: "linux"