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_PARAMETER, "Cannot open wallet dump file");
        }
        CHECK_NONFATAL(pwallet->chain().findBlock(pwallet->GetLastBlockHash(), FoundBlock().time(nTimeBegin)));
        int64_t nFilesize = std::max((int64_t)1, (int64_t)file.tellg());
        file.seekg(0, file.beg);
        
        
        pwallet->chain().showProgress(strprintf("%s " + _("Importing…").translated, pwallet->GetDisplayName()), 0, false); // 
        std::vector<std::tuple<CKey, int64_t, bool, std::string>> keys;
        std::vector<std::pair<CScript, int64_t>> scripts;
        while (file.good()) {
            pwallet->chain().showProgress("", std::max(1, std::min(50, (int)(((double)file.tellg() / (double)nFilesize) * 100))), false);
            std::string line;
            std::getline(file, line);
            if (line.empty() || line[0] == '#')
                continue;
            std::vector<std::string> vstr;
            boost::split(vstr, line, boost::is_any_of(" "));
            if (vstr.size() < 2)
                continue;
            CKey key = DecodeSecret(vstr[0]);
            if (key.IsValid()) {
                int64_t nTime = ParseISO8601DateTime(vstr[1]);
                std::string strLabel;
                bool fLabel = true;
                for (unsigned int nStr = 2; nStr < vstr.size(); nStr++) {
                    if (vstr[nStr].front() == '#')
                        break;
                    if (vstr[nStr] == "change=1")
                        fLabel = false;