JT400: refactor test to avoid CPF2451 correctly

[JiriOndrusek]

Bug description

Current implementation of jt400 test coverage with a real server clears data not optimally, because of CPF2451 Message queue REPLYMSGQ is allocated to another job. The reason of the error is the timeout of connection pool used by jt400 component (which is by default 30 seconds). It should be possible to set timeout to 0 and refactor clearing of the resource to happen after the execution of the tests (not before). This should make fix proposed by #6018 better.