[lib] Check keyserver connection in request-response-handler

Summary:
getClientResponses is already keyserver-specific and aware of the keyserver id, so the only needed change for this handler is to select a proper connection status.

https://linear.app/comm/issue/ENG-5780/update-requestresponsehandler

Depends on D11184

Test Plan: Add some console logs checking if we select the connection.

Reviewers: michal, atul, inka, kamil

Reviewed By: michal

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11185