Revert "RESTRICT AUTOMERGE Set BUILD_ID=SC"

This reverts commit 52f01727725336f82e1f739858502f0a257882d5.

Reason for revert: broke bramble boot test

Bug: 196357202
Change-Id: Ib6f05cd323109076cbc6693d16a74cd1d86a6849
diff --git a/core/build_id.mk b/core/build_id.mk
index 84429d2..2f9c3f3 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=SC
+BUILD_ID=MASTER