test: use bitcoin default dustrelayfee in mempool_accept.py

Author: delta1

test/functional/mempool_accept.py

@@ -46,6 +46,7 @@ def set_test_params(self):
             '-txindex',
             '-txindex','-permitbaremultisig=0',
             '-multi_data_permitted=1', # Elements test
+            '-dustrelayfee=0.00003000', # ELEMENTS: use the Bitcoin default dust relay fee rate
         ]] * self.num_nodes
         self.supports_cli = False