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 (vstr[nStr] == "reserve=1")
                        fLabel = false;
                    if (vstr[nStr].substr(0,6) == "label=") {
                        strLabel = DecodeDumpString(vstr[nStr].substr(6));
                        fLabel = true;
                    }
                }
                keys.push_back(std::make_tuple(key, nTime, fLabel, strLabel));
            } else if(IsHex(vstr[0])) {
                std::vector<unsigned char> vData(ParseHex(vstr[0]));
                CScript script = CScript(vData.begin(), vData.end());
                int64_t birth_time = ParseISO8601DateTime(vstr[1]);
                scripts.push_back(std::pair<CScript, int64_t>(script, birth_time));
            }
        }
        file.close();
        // 
        if (keys.size() > 0 && pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
            pwallet->chain().showProgress("", 100, false); // 
            throw JSONRPCError(RPC_WALLET_ERROR, "Importing wallets is disabled when private keys are disabled");
        }
        double total = (double)(keys.size() + scripts.size());
        double progress = 0;
        for (const auto& key_tuple : keys) {
            pwallet->chain().showProgress("", std::max(50, std::min(75, (int)((progress / total) * 100) + 50)), false);
            const CKey& key = std::get<0>(key_tuple);
            int64_t time = std::get<1>(key_tuple);
            bool has_label = std::get<2>(key_tuple);
            std::string label = std::get<3>(key_tuple);
            CPubKey pubkey = key.GetPubKey();