When a workflow is setup the routing rules are setup so that reads/writes to the target shards
still go to the source shard since the target is not yet setup. If SwitchReads is called without
-reverse then the routing rules for the target keyspace are setup to actually use it. It is assumed
that the workflow was successful and user is ready to use the target keyspace now.
However if, for any reason, we want to abort this workflow using the -reverse flag deletes the
rules that were setup and vtgate will route the queries to this table to the the source table.
There is no way to reverse the use of the -reverse flag other than by recreating the routing rules
again using the vtctl ApplyRoutingRules command.