Set the container field of aconfig flags

Test: m
Bug: 312769710
Change-Id: I366717c7139886e30360914256ad7710da5095e9
diff --git a/fsverity_init/flags.aconfig b/fsverity_init/flags.aconfig
index 20640d7..495c71c 100644
--- a/fsverity_init/flags.aconfig
+++ b/fsverity_init/flags.aconfig
@@ -1,4 +1,5 @@
 package: "android.security.flag"
+container: "system"
 
 flag {
     name: "deprecate_fsverity_init"