Set level of logger dataplane to error (#1838)

When we run the fdb/test_fdb.py script, the `dataplane` logger generats
**too** much log messages at warning level. This change sets log level
of the `dataplne` logger to error to filter out the warning messages.

Signed-off-by: Xin Wang <xiwang5@microsoft.com>

tests/conftest.py

@@ -169,7 +169,7 @@ def config_logging(request):
     # Filter out unnecessary logs generated by calling the ptfadapter plugin
     dataplane_logger = logging.getLogger("dataplane")
     if dataplane_logger:
-        dataplane_logger.setLevel(logging.WARNING)
+        dataplane_logger.setLevel(logging.ERROR)
 
 
 @pytest.fixture(scope="session")