Fix cli dimensions filtering in TestRunner

With AZ Override changes, region dimension may contain
an AZ that has to be unmarshalled, but only if the
dimension has a value that is not None.

Signed-off-by: Nicola Sirena <[email protected]>

Author: NSsirena

tests/integration-tests/conftest_tests_config.py

@@ -87,7 +87,7 @@ def apply_cli_dimensions_filtering(config, items):
     allowed_values = {}
     for dimension in DIMENSIONS_MARKER_ARGS:
         values = config.getoption(dimension + "s")
-        if dimension == "region":
+        if dimension == "region" and values is not None:
             # values may contain a list of az_id/regions.
             # We have to unmarshal any of them in case one or more overrides were specified
             values = [unmarshal_az_override(v) for v in values]