Rename use_case use_test_keys in manifest

Author: fbeutin-ledger

ledger_app.toml

@@ -5,7 +5,7 @@ devices = ["nanos", "nanox", "nanos+", "stax"]
 
 [use_cases] # Coherent build options that make sense for your application
 debug = "DEBUG=1"
-set_test_keys = "DEBUG=1 CAL_TEST_KEY=1 DOMAIN_NAME_TEST_KEY=1 SET_PLUGIN_TEST_KEY=1 NFT_TEST_KEY=1"
+use_test_keys = "DEBUG=1 CAL_TEST_KEY=1 DOMAIN_NAME_TEST_KEY=1 SET_PLUGIN_TEST_KEY=1 NFT_TEST_KEY=1"
 cal_bypass = "DEBUG=1 BYPASS_SIGNATURES=1"
 
 [tests]