Reduce redundant secondary index selection lookups

Once an index has been identified as being the one that should be used for a given query, it should be included as part of the ReadCommand so that it can be retrieved when needed during execution. Currently we don't do this, meaning that the index selection process implemented in SIM::getBestIndexFor is run multiple times on both the coordinator and each replica when performing a range command.

This is also a pre-requisite of CASSANDRA-10214