…t compiled

0c845e3 test: Fix wallet_listdescriptors.py if bdb is not compiled (Hennadii Stepanov)

Pull request description:

  If build system is configured `--without-bdb`, the `wallet_listdescriptors.py` fails:
  ```
  $ test/functional/wallet_listdescriptors.py --descriptors
  2021-07-14T13:20:52.931000Z TestFramework (INFO): Initializing test directory /tmp/bitcoin_func_test_02p7o1c9
  2021-07-14T13:21:23.377000Z TestFramework (INFO): Test that the command is not available for legacy wallets.
  2021-07-14T13:21:23.381000Z TestFramework (ERROR): JSONRPC error
  Traceback (most recent call last):
    File "/home/hebasto/GitHub/bitcoin/test/functional/test_framework/test_framework.py", line 128, in main
      self.run_test()
    File "test/functional/wallet_listdescriptors.py", line 34, in run_test
      node.createwallet(wallet_name='w1', descriptors=False)
    File "/home/hebasto/GitHub/bitcoin/test/functional/test_framework/test_node.py", line 685, in createwallet
      return self.__getattr__('createwallet')(wallet_name, disable_private_keys, blank, passphrase, avoid_reuse, descriptors, load_on_startup, external_signer)
    File "/home/hebasto/GitHub/bitcoin/test/functional/test_framework/coverage.py", line 47, in __call__
      return_val = self.auth_service_proxy_instance.__call__(*args, **kwargs)
    File "/home/hebasto/GitHub/bitcoin/test/functional/test_framework/authproxy.py", line 146, in __call__
      raise JSONRPCException(response['error'], status)
  test_framework.authproxy.JSONRPCException: Compiled without bdb support (required for legacy wallets) (-4)
  2021-07-14T13:21:23.436000Z TestFramework (INFO): Stopping nodes
  2021-07-14T13:21:24.092000Z TestFramework (WARNING): Not cleaning up dir /tmp/bitcoin_func_test_02p7o1c9
  2021-07-14T13:21:24.092000Z TestFramework (ERROR): Test failed. Test logging available at /tmp/bitcoin_func_test_02p7o1c9/test_framework.log
  2021-07-14T13:21:24.092000Z TestFramework (ERROR):
  2021-07-14T13:21:24.092000Z TestFramework (ERROR): Hint: Call /home/hebasto/GitHub/bitcoin/test/functional/combine_logs.py '/tmp/bitcoin_func_test_02p7o1c9' to consolidate all logs
  2021-07-14T13:21:24.092000Z TestFramework (ERROR):
  2021-07-14T13:21:24.092000Z TestFramework (ERROR): If this failure happened unexpectedly or intermittently, please file a bug and provide a link or upload of the combined log.
  2021-07-14T13:21:24.092000Z TestFramework (ERROR): https://github.com/bitcoin/bitcoin/issues
  2021-07-14T13:21:24.092000Z TestFramework (ERROR):
  ```

  This PR fixes this issue.

  Also see bitcoin#20267.

ACKs for top commit:
  achow101:
    ACK 0c845e3

Tree-SHA512: d7116a9ae30c7b7e3f55f55d2eea66f9e293c38d6757ed66d0477e4256ff5fedca5ddedafa0ef0c09f4dc1f7f973163e5a46090da26b067fdddbd9ea2ee76633