Subscription IT: explicitly declare `setUp` method for test class to avoid `UNKNOWN-IT` test class name

[VGalaxies]

See the logic in org.apache.iotdb.it.env.cluster.env.AbstractEnv#getTestClassName, although some pipe tests can also obtain the test class name without being declared, such as org.apache.iotdb.pipe.it.manual.IoTDBPipeInclusionIT#testPureSchemaInclusion, which may be caused by the multi-inheritance hierarchy of the subscription IT...