Fix an unit test failure on ambari-metrics-host-monitoring

$ mvn test -f ambari-metrics-host-monitoring/pom.xml

...

[INFO] --- exec-maven-plugin:1.2.1:exec (python-test) @ ambari-metrics-host-monitoring ---
Running tests
No handlers could be found for logger "root"
Traceback (most recent call last):
  File "unitTests.py", line 137, in <module>
    sys.exit(main())
  File "unitTests.py", line 106, in main
    modules]
  File "/usr/lib/python2.7/unittest/loader.py", line 91, in loadTestsFromName
    module = __import__('.'.join(parts_copy))
  File "/home/sekikn/repos/ambari-metrics/ambari-metrics-host-monitoring/src/test/python/core/TestMetricCollector.py", line 24, in <module>
    from core.application_metric_map import ApplicationMetricMap
  File "/home/sekikn/repos/ambari-metrics/ambari-metrics-host-monitoring/src/main/python/core/__init__.py", line 29, in <module>
    for dir in os.walk(path).next()[1]:
StopIteration
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.126 s
[INFO] Finished at: 2023-02-24T09:45:36+09:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec (python-test) on project ambari-metrics-host-monitoring: Command execution failed.: Process exited with an error: 1 (Exit value: 1) -> [Help 1]