Search on a shard group while relocation final flip happens might fail

make sure relocation shards add their corresponding initializing shard routing when search across initializing shards

also, make shardFailures lazy again

closes #3427
Search on a shard group while relocation final flip happens might fail

make sure relocation shards add their corresponding initializing shard routing when search across initializing shards

also, make shardFailures lazy again

closes #3427