Change default Thrift Server implementation to TThreadedSelectorServer

[dlmarion]

Change the default Thrift server to TThreadedSelectorServer.
Validate that the client IP is being handled and logged correctly in this server type.

[dlmarion]

TThreadedSelectorServer suffered from an issue which was fixed in https://issues.apache.org/jira/browse/THRIFT-5230 included in Thrift version 0.21. Recent testing has shown better performance than THsHaServer. We should be able to use this server type now since our Thrift dependency is > 0.21.

[dlmarion]

#6454 should probably be merged before this task is started as it modifies related code.

[ddanielr]

We could probably target 2.1 with this change and merge it to main