Hedged reads are deprecated and are set to be removed in 9.0, but we still need to accept the option without erroring to avoid breaking API compatibility. To alert users that they may be specifying options that have no effect, we should introduce a log warning whenever hedging options are received. A good place to put this is in ParseAndRunCommand::_parseCommand.

To avoid spamming the logs, we should rate limit this (e.g. at most once per minute).