slight refactor of get_operational_status behavior

This patch adjusts the logic of IMS get_operational_status to leverage the checks that are already done in the status_builder functions that it calls.  

Passes the following tests:
* ion.services.sa.instrument.test.test_instrument_management_service_integration:TestInstrumentManagementServiceIntegration.test_resources_associations_extensions 
* ion.services.sa.observatory.test.test_observatory_management_service_integration:TestObservatoryManagementServiceIntegration.test_observatory_extensions 
* ion.services.sa.observatory.test.test_observatory_management_service_integration:TestObservatoryManagementServiceIntegration.test_observatory_org_extended 
* ion.services.sa.observatory.test.test_platform_launch:TestPlatformLaunch.test_platform_device_extended_attributes