The `dumpwallet` RPC command throws an error at the signet node and stops it.
~~This does not happen in mainnet or testnet, where the command worked successfully in my tests..~~
Originally this error was only happening on signet, but it also happened on testnet after it worked successfully for a while.

**Expected behavior**

The RPC `dumpwallet` command is expected to return a success message and create the dump file that contains the private keys.

**Actual behavior**

The command returns an error on client side (`bitcoin-cli`):
`error: timeout on transient error: Could not connect to the server 127.0.0.1:38332 (error code 1 - "EOF reached")
Make sure the bitcoind server is running and that you are connecting to the correct RPC port.`

And it throws an error at the signet node and stops it.

```
POTENTIAL DEADLOCK DETECTED
Previous lock order was:
  'cs_wallet' in wallet/wallet.cpp:2860 (in thread 'httpworker.1')
  (2) '::cs_main' in node/interfaces.cpp:687 (in thread 'httpworker.1')
  'm_node.mempool->cs' in node/interfaces.cpp:687 (in thread 'httpworker.1')
  'cs_wallet' in wallet/wallet.cpp:1204 (in thread 'httpworker.1')
  (1) 'cs_KeyStore' in script/signingprovider.cpp:165 (in thread 'httpworker.1')
Current lock order is:
  'wallet.cs_wallet' in wallet/rpcdump.cpp:743 (in thread 'httpworker.3')
  (1) 'spk_man.cs_KeyStore' in wallet/rpcdump.cpp:743 (in thread 'httpworker.3')
  (1) 'spk_man->cs_KeyStore' in wallet/wallet.cpp:2303 (in thread 'httpworker.3')
  (2) 'cs_main' in node/interfaces.cpp:493 (in thread 'httpworker.3')
Assertion failed: detected inconsistent lock order for 'cs_main' in node/interfaces.cpp:493 (in thread 'httpworker.3'), details in debug log.
Aborted (core dumped)
```

**To reproduce**

Start the node on signet mode:
`bitcoind -signet`

And dump an existing wallet:
`bitcoin-cli -signet -rpcwallet="legacy_wallet_01" dumpwallet "filename"`

**System information**

The bitcoin node was compiled from master (commit: `df2b5dadfb2dc21b05e5a60b71987fb5b96201f5`)
Ubuntu 20.04, 8 CPUs, 12 GiB RAM and SSD.

if (!error.empty()) {
            warnings.push_back("Importing as non-solvable: " + error + ". If this is intentional, don't provide any keys, pubkeys, witnessscript, or redeemscript.");
            import_data = ImportData();
            pubkey_map.clear();
            privkey_map.clear();
            have_solving_data = false;
        } else {
            // 
            if (import_data.redeemscript) warnings.push_back("Ignoring redeemscript as this is not a P2SH script.");
            if (import_data.witnessscript) warnings.push_back("Ignoring witnessscript as this is not a (P2SH-)P2WSH script.");
            for (auto it = privkey_map.begin(); it != privkey_map.end(); ) {
                auto oldit = it++;
                if (import_data.used_keys.count(oldit->first) == 0) {
                    warnings.push_back("Ignoring irrelevant private key.");
                    privkey_map.erase(oldit);
                }
            }
            for (auto it = pubkey_map.begin(); it != pubkey_map.end(); ) {
                auto oldit = it++;
                auto key_data_it = import_data.used_keys.find(oldit->first);
                if (key_data_it == import_data.used_keys.end() || !key_data_it->second) {
                    warnings.push_back("Ignoring public key \"" + HexStr(oldit->first) + "\" as it doesn't appear inside P2PKH or P2WPKH.");
                    pubkey_map.erase(oldit);
                }
            }
        }
    }
    return warnings;
}
static UniValue ProcessImportDescriptor(ImportData& import_data, std::map<CKeyID, CPubKey>& pubkey_map, std::map<CKeyID, CKey>& privkey_map, std::set<CScript>& script_pub_keys, bool& have_solving_data, const UniValue& data, std::vector<CKeyID>& ordered_pubkeys)