Include default Android Things AVB keys in otatools.zip

Android Things has an extension on AVB and thus uses different test
keys, along with a public key metadata file. See external/avb/README.md.

Bug: 72837107
Test: Local sign_target_files_apks run of locally built target-files
Change-Id: I769e09a971b9b6b2c9cb0f3272f756b1857eb286
diff --git a/core/Makefile b/core/Makefile
index 0b7950b..706b371 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -2401,6 +2401,8 @@
 
 OTATOOLS_DEPS := \
   system/extras/ext4_utils/mke2fs.conf \
+  external/avb/test/data/atx_metadata.bin \
+  external/avb/test/data/testkey_atx_psk.pem \
   external/avb/test/data/testkey_rsa4096.pem \
   $(sort $(shell find system/update_engine/scripts -name \*.pyc -prune -o -type f -print)) \
   $(sort $(shell find build/target/product/security -type f -name \*.x509.pem -o -name \*.pk8 -o \