For convertToCapped, router should not check if the collection is sharded itself

Currently the router checks its cache to see if the collection is sharded, and fails the convertToCapped operation if so. This is incorrect because the router's cache might be stale.

Instead, the router should rely on the shard to check whether the collection is sharded.

The router already attaches shardVersion, but the shard should actually check the shardVersion, which it does not currently do.