Why do you bother with sharding if you only have one shard?
It is highly not recommended to run 2 arbiters on the same replica set.
You are wasting resources while adding latency and complexity. Running multiple instances on the same physical hardware is most likely resulting in reduce performance as the difference instances are battling for shared resources.
As to temporary fix your problem of unavailability you may do the NON RECOMMENDED configuration.
Connect to server-3 configuration server and remove the server-1 and server-2 members. Do the same with your shard replica set. Starts 3 new instances on server-3. Add one to the configuration server replica set as a data bearing node. Add 2nd new instance to the configuration server replica set as an arbiter. Finally add the third new instances as data bearing node to your shard replica set.
If your a little bit experienced with file system operations, you may seed the 2 load bearing instances with file system snapshot from the current load bearing nodes with data.
This will give you:
. 1 mongos
. 1 PSA configuration for the configuration server
. 1 PSA configuration for your shard
Depending of the amount of data and capability of server-3 this configuration will struggle, but it might be functional.
But if you can, just run one single normal PSA if you only have 1 physical.