soong: Hardcode release-keys instead of dev-keys

- We sign inline.

Change-Id: Idfac2f3a48973a3068da48f04724d5fa4ee5e934
Signed-off-by: Cyber Knight <cyberknight755@gmail.com>

scripts/gen_build_prop.py

@@ -43,7 +43,7 @@ def get_build_keys(product_config):
   default_cert = product_config.get("DefaultAppCertificate", "")
   if default_cert == "" or default_cert == os.path.join(TEST_KEY_DIR, "testKey"):
     return "test-keys"
-  return "dev-keys"
+  return "release-keys"
 
 def parse_args():
   """Parse commandline arguments."""