[automerge] Revert "Revert "RESTRICT AUTOMERGE Set BUILD_ID=SC"" 2p: ef1bcc1f9a

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/15798253

Bug: 196178071
Change-Id: I78ad7c9c835ec51dffe54baeb3f896324cfa42eb
diff --git a/core/build_id.mk b/core/build_id.mk
index 2f9c3f3..84429d2 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-BUILD_ID=MASTER
+BUILD_ID=SC