test: add coverage for unknown address type for `createwalletdescriptor` #31635

Calling createwalletdescriptor RPC with an unknown address type throws an error. This PR adds test coverage for it as done for other RPCs (getnewaddress , getrawchangeaddress, etc).

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31635.

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https://github.com/bitcoin/bitcoin/actions/runs/12711073565/job/35433597593?pr=31635#step:7:44312:

 test  2025-01-10T14:30:30.975000Z TestFramework (ERROR): Assertion failed 
                                   Traceback (most recent call last):
                                     File "/home/runner/work/_temp/test/functional/test_framework/util.py", line 160, in try_rpc
                                       fun(*args, **kwds)
                                     File "/home/runner/work/_temp/test/functional/test_framework/coverage.py", line 50, in __call__
                                       return_val = self.auth_service_proxy_instance.__call__(*args, **kwargs)
                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                                     File "/home/runner/work/_temp/test/functional/test_framework/authproxy.py", line 146, in __call__
                                       raise JSONRPCException(response['error'], status)
                                   test_framework.authproxy.JSONRPCException: createwalletdescriptor is not available for non-descriptor wallets (-4)
                                   During handling of the above exception, another exception occurred:
                                   Traceback (most recent call last):
                                     File "/home/runner/work/_temp/test/functional/test_framework/test_framework.py", line 135, in main
                                       self.run_test()
                                     File "/home/runner/work/_temp/ci/scratch/build-x86_64-pc-linux-gnu/test/functional/wallet_address_types.py", line 372, in run_test
                                       assert_raises_rpc_error(-5, "Unknown address type 'bech23'", self.nodes[3].createwalletdescriptor, "bech23")
                                     File "/home/runner/work/_temp/test/functional/test_framework/util.py", line 151, in assert_raises_rpc_error
                                       assert try_rpc(code, message, fun, *args, **kwds), "No exception raised"
                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                                     File "/home/runner/work/_temp/test/functional/test_framework/util.py", line 164, in try_rpc
                                       raise AssertionError("Unexpected JSONRPC error code %i" % e.error["code"])
                                   AssertionError: Unexpected JSONRPC error code -4
 test  2025-01-10T14:30:31.007000Z TestFramework (DEBUG): Closing down network thread

Thanks, @fanquake. Fixed.

tACK 4da7bfdcc902f22239e55cd9b90abf36b29edfde

Pretty straightforward change.

lgtm ACK 4da7bfdcc902f22239e55cd9b90abf36b29edfde

rfm?