Add ro.keystore.boot_level_key.strategy

Bug: 241241178
Test: set property on Cuttlefish, check logs for strategy used.
Change-Id: Ifaaec811316c43fdae232f9a08c5d862011ccc71
diff --git a/private/keystore.te b/private/keystore.te
index 78c0198..8e681b1 100644
--- a/private/keystore.te
+++ b/private/keystore.te
@@ -26,6 +26,7 @@
 # Keystore need access to the keystore_key context files to load the keystore key backend.
 allow keystore keystore2_key_contexts_file:file r_file_perms;
 
+# Allow keystore to listen to changing boot levels
 get_prop(keystore, keystore_listen_prop)
 
 # Keystore needs to transfer binder references to vold so that it