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.

throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid redeem script \"" + strRedeemScript + "\": must be hex string");
        }
        auto parsed_redeemscript = ParseHex(strRedeemScript);
        import_data.redeemscript = std::make_unique<CScript>(parsed_redeemscript.begin(), parsed_redeemscript.end());
    }
    if (witness_script_hex.size()) {
        if (!IsHex(witness_script_hex)) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid witness script \"" + witness_script_hex + "\": must be hex string");
        }
        auto parsed_witnessscript = ParseHex(witness_script_hex);
        import_data.witnessscript = std::make_unique<CScript>(parsed_witnessscript.begin(), parsed_witnessscript.end());
    }
    for (size_t i = 0; i < pubKeys.size(); ++i) {
        const auto& str = pubKeys[i].get_str();
        if (!IsHex(str)) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Pubkey \"" + str + "\" must be a hex string");
        }
        auto parsed_pubkey = ParseHex(str);
        CPubKey pubkey(parsed_pubkey);
        if (!pubkey.IsFullyValid()) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Pubkey \"" + str + "\" is not a valid public key");
        }
        pubkey_map.emplace(pubkey.GetID(), pubkey);
        ordered_pubkeys.push_back(pubkey.GetID());
    }
    for (size_t i = 0; i < keys.size(); ++i) {
        const auto& str = keys[i].get_str();
        CKey key = DecodeSecret(str);
        if (!key.IsValid()) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid private key encoding");