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.
{
    int target = value.get_int();
    unsigned int max_target = ::feeEstimator.HighestTargetTracked(FeeEstimateHorizon::LONG_HALFLIFE);
    if (target < 1 || (unsigned int)target > max_target) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid conf_target, must be between %u - %u", 1, max_target));
    }
    return (unsigned int)target;
}
/**
 * Return average network hashes per second based on the last 'lookup' blocks,
 * or from the last difficulty change if 'lookup' is nonpositive.
 * If 'height' is nonnegative, compute the estimate at the time when a given block was found.
 */
static UniValue GetNetworkHashPS(int lookup, int height) {