Merge #19204: p2p: Reduce inv traffic during IBD

fa525e4d1c net: Avoid wasting inv traffic during IBD (MarcoFalke)
fa06d7e934 refactor: block import implies IsInitialBlockDownload (MarcoFalke)
faba65e696 Add ChainstateManager::ActiveChainstate (MarcoFalke)
fabf3d64ff test: Add FeeFilterRounder test (MarcoFalke)

Pull request description:

  Tx-inv messages are ignored during IBD, so it would be nice if we told peers to not send them in the first place. Do that by sending two `feefilter` messages: One when the connection is made (and the node is in IBD), and another one when the node leaves IBD.

ACKs for top commit:
  jamesob:
    ACK fa525e4d1c ([`jamesob/ackr/19204.1.MarcoFalke.p2p_reduce_inv_traffic_d`](https://github.com/jamesob/bitcoin/tree/ackr/19204.1.MarcoFalke.p2p_reduce_inv_traffic_d))
  naumenkogs:
    utACK fa525e4
  gzhao408:
    ACK fa525e4d1c
  jonatack:
    re-ACK fa525e4 checked diff `git range-diff 19612ca fa8a66c fa525e4`, re-reviewed, ran tests, ran a custom p2p IBD behavior test at 9321e0f223.
  hebasto:
    re-ACK fa525e4d1c, only rebased since the [previous](https://github.com/bitcoin/bitcoin/pull/19204#pullrequestreview-429519667) review (verified with `git range-diff`).

Tree-SHA512: 2c22a5def9822396fca45d808b165b636f1143c4bdb2eaa5c7e977f1f18e8b10c86d4c180da488def38416cf3076a26de15014dfd4d86b2a7e5af88c74afb8eb

test/functional/rpc_net.py

@@ -46,10 +46,12 @@ class NetTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 2
-        self.extra_args = [["-minrelaytxfee=0.00001000"],["-minrelaytxfee=0.00000500"]]
+        self.extra_args = [["-minrelaytxfee=0.00001000"], ["-minrelaytxfee=0.00000500"]]
         self.supports_cli = False
 
     def run_test(self):
+        self.log.info('Get out of IBD for the minfeefilter test')
+        self.nodes[0].generate(1)
         self.log.info('Connect nodes both way')
         connect_nodes(self.nodes[0], 1)
         connect_nodes(self.nodes[1], 0)