Today, NetworkInterface::startExhaustCommand kicks off recursive tasks for reading exhaust responses and passes each to an argument-provided callback. This prevents callers from specifying when they're ready to receive the next response, which can easily lead to bugs in practice.

We should update NI::startExhaustCommand to return an ExhaustResponseReader (implemented in SERVER-93113) instead. As part of this, we'll need to move the recursive exhaust response work scheduling into ThreadPoolTaskExecutor, rather than in NetworkInterfaceTL. See the design for more details.