[tests] set default node parameters (#6593)

This commit set default node parameters and remove unnecessary
parameters in topologies.
- router selection jitter to 1s
- panid to 0xface

tests/scripts/thread-cert/test_ipv6_source_selection.py

@@ -48,7 +48,6 @@ class TestIPv6SourceSelection(thread_cert.TestCase):
         ROUTER: {
             'mode': 'rdn',
             'panid': 0xcafe,
-            'router_selection_jitter': 1,
             'allowlist': [LEADER]
         },
     }