The `generate` RPC method:
- was introduced in 2010
- is now only used for testing
- reaches across multiple components (wallet, mining)

I propose we remove the wallet `generate` RPC method and update all tests to use the `generatetoaddress` RPC method. We can do this non-invasively in the test framework by adding a `generate` method to `TestNode` so that the individual tests do not need to be updated. We could also add a `generate` alias to the `generatetoaddress` RPC method.

Doing this removes a wallet->server dependency and simplifies the wallet->server interface (#10973).

I'm opening this issue before implementing in case anyone has objections.
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() != 0)
        throw std::runtime_error(
            "listaddressgroupings\n"
            "\nLists groups of addresses which have had their common ownership\n"
            "made public by common use as inputs or as the resulting change\n"
            "in past transactions\n"
            "\nResult:\n"
            "[\n"
            "  [\n"
            "    [\n"
            "      \"address\",            (string) The bitcoin address\n"
            "      amount,                 (numeric) The amount in " + CURRENCY_UNIT + "\n"
            "      \"label\"               (string, optional) The label\n"
            "    ]\n"
            "    ,...\n"
            "  ]\n"
            "  ,...\n"