[tests] Rename NodeConn and NodeConnCB

NodeConn -> P2PConnection
NodeConnCB -> P2PInterface

test/functional/assumevalid.py

@@ -39,14 +39,14 @@ from test_framework.mininode import (CBlockHeader,
                                      CTxIn,
                                      CTxOut,
                                      NetworkThread,
-                                     NodeConnCB,
+                                     P2PInterface,
                                      msg_block,
                                      msg_headers)
 from test_framework.script import (CScript, OP_TRUE)
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal
 
-class BaseNode(NodeConnCB):
+class BaseNode(P2PInterface):
     def send_header_for_blocks(self, new_blocks):
         headers_message = msg_headers()
         headers_message.headers = [CBlockHeader(b) for b in new_blocks]