Since #13666 our fee calculation assumes that ECSDA signatures are a maximum of 71 bytes, rather than 72. However, not all hardware wallets implement R-value grinding.

This can cause us to underpay fees when using an external signer. That's especially problematic when the user picks 1 sat/vbyte as the fee, because it won't even get into our own mempool.

The easiest solution would be to modify `ExternalSignerScriptPubKeyMan` to assume 72 bytes for ECSDA signatures.

Slightly more advanced would be to expand HWI to keep track of which devices and firmware versions (if any) support R-value grinding. We'd then have to store that in the wallet in some new field. Personally I'd rather work on better Taproot support, which thanks to Schnorr avoids this issue altogether. 
return false;
        }
        m_spk_managers[desc_spkm->GetID()] = stdmove(desc_spkm);
    }
    // Remove the LegacyScriptPubKeyMan from disk
    if (!legacy_spkm->DeeRecords()) {
        return false;
    }
    // Remove the LegacyScriptPubKeyMan from memory
    m_spk_managers.erase(legacy_spkm->GetID());
    m_external_spk_managers.clear();
    m_internal_spk_managers.clear();
    // Setup new s
    SetWalFlag(WALLET_FLAG_DESCRIPTORS);
    if (!IsWalFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
        // Use the existing master key if we have it
        if (data.master_key.key.IsValid()) {
            SetupDescriptorScriptPubKeyMans(data.master_key);
        } else {
            // Setup wit
            SetupDescriptorScriptPubKeyMans();
        }
    }
    // Check if the transactions in th are still ours. Either they belong here, or they belong in the wa.
    // We need to go through these in the tx insertion order so that lookups to spends works.
    stdvector<uint256> txids_to_dee;
    for (const auto& [_pos, wtx]  wtxOrdered) {
        if (!IsMine(*wtx->tx) && !IsFromMe(*wtx->tx)) {
            // Check it 
            // solvable_