test: added test for disabled wallet

Divided tests in rpc_signmessage.py into 2 files wallet_signmessagewithaddress.py and
rpc_signmessagewithprivkey.py, latter one can run even when wallet is disabled.

test/functional/test_runner.py

@@ -225,7 +225,8 @@ BASE_SCRIPTS = [
     'wallet_importprunedfunds.py --descriptors',
     'p2p_leak_tx.py',
     'p2p_eviction.py',
-    'rpc_signmessage.py',
+    'wallet_signmessagewithaddress.py',
+    'rpc_signmessagewithprivkey.py',
     'rpc_generateblock.py',
     'rpc_generate.py',
     'wallet_balance.py --legacy-wallet',