The justification for the original decision based on this comment, server docs and the spec component of DRIVERS-383 call out that (a) you should tune this at the OS level and (b) "there is no demonstrated benefit to allowing it to be disabled".

If however certain environments (such as Azure) where OS KeepAlive can't be tuned and the default keepalive is known to be lower (120 seconds) there may be value in allowing this to be client-configurable.

Let's keep the defaults that have been set but restore the ability to configure keepAliveInitialDelay (note that keepAlive should still not be toggleable) (ex: was removed in NODE-5190)