Merge bitcoin/bitcoin#25439: rpc: Return incrementalrelayfee in getmempoolinfo

fafee78188 rpc: Return incrementalrelayfee in getmempoolinfo (MacroFake)

Pull request description:

  Seems odd to return other policy info, but not the incremental relay fee

ACKs for top commit:
  1440000bytes:
    ACK https://github.com/bitcoin/bitcoin/pull/25439/commits/fafee78188c3de5f6245ec769429822ca4b98c63
  w0xlt:
    Code Review ACK https://github.com/bitcoin/bitcoin/pull/25439/commits/fafee78188c3de5f6245ec769429822ca4b98c63
  jarolrod:
    tACK fafee78188

Tree-SHA512: faad0af6c039b8257acbeac913bc5dcdb2ea2db304c95e52601536c8de60eb1186e9fbb4a64a68adf476605f18022aeda16a5644a0d7912592b0977e4c029638

test/functional/feature_rbf.py

@@ -711,6 +711,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
 
         # Higher fee, higher feerate, different txid, but the replacement does not provide a relay
         # fee conforming to node's `incrementalrelayfee` policy of 1000 sat per KB.
+        assert_equal(self.nodes[0].getmempoolinfo()["incrementalrelayfee"], Decimal("0.00001"))
         tx.vout[0].nValue -= 1
         assert_raises_rpc_error(-26, "insufficient fee", self.nodes[0].sendrawtransaction, tx.serialize().hex())