tests: Tests for inactive HD chains

test cases are added for inactive HD chains: a basic case, a case
where the wallet is encrypted, and a case for the 21605 segfault.

test/functional/test_framework/test_node.py

@@ -698,6 +698,9 @@ class RPCOverloadWrapper():
     def __getattr__(self, name):
         return getattr(self.rpc, name)
 
+    def createwallet_passthrough(self, *args, **kwargs):
+        return self.__getattr__("createwallet")(*args, **kwargs)
+
     def createwallet(self, wallet_name, disable_private_keys=None, blank=None, passphrase='', avoid_reuse=None, descriptors=None, load_on_startup=None, external_signer=None):
         if descriptors is None:
             descriptors = self.descriptors