Merge #18807: [doc / test / mempool] unbroadcast follow-ups

9e1cb1adf1 [trivial/doc] Fix comment type (Amiti Uttarwar)
8f30260a67 [doc] Update unbroadcast description in RPC results (Amiti Uttarwar)
750456d6f2 [trivial] Remove misleading 'const' (Amiti Uttarwar)
fa32e676e5 [test] Manage node connections better in mempool persist test (Amiti Uttarwar)
1f94bb0c74 [doc] Provide rationale for randomization in scheduling. (Amiti Uttarwar)
9c8a55d9cb [mempool] Don't throw expected error message when upgrading (Amiti Uttarwar)
ba54983182 [test] Test that wallet transactions aren't rebroadcast before 12 hours (Amiti Uttarwar)
00d44a534b [test] P2P connection behavior should meet expectations (Amiti Uttarwar)
bd093ca15d [test] updates to unbroadcast test (Amiti Uttarwar)
dab298d9ab [docs] add release notes (Amiti Uttarwar)

Pull request description:

  This PR is a follow up to #18038 which introduced the idea of an unbroadcast set & focuses mostly on documentation updates and test fixes. One small functionality update to not throw an expected error in `LoadMempool` when you upgrade software versions.

  #18895 is another follow up to that addresses other functionality updates.

  Background context:
  The unbroadcast set is a mechanism for the mempool to track locally submitted transactions (via wallet or RPC). The node does a best-effort of delivering the transactions to the network via retries every 10-15 minutes until either a `GETDATA` is received or the transaction is removed from the mempool.

ACKs for top commit:
  MarcoFalke:
    ACK 9e1cb1adf1 👁
  gzhao408:
    ACK [`9e1cb1a`](9e1cb1adf1)

Tree-SHA512: 0cd51c4ca368b9dce92d50d73ec6e9df278a259e609eef2858f24cb8595ad07acc3db781d9eb0c351715f18fca5a2b4526838981fdb34a522427e9dc868bdaa6

test/functional/test_framework/mininode.py

@@ -655,6 +655,8 @@ class P2PTxInvStore(P2PInterface):
                 # save txid
                 self.tx_invs_received[i.hash] += 1
 
+        super().on_inv(message)
+
     def get_invs(self):
         with mininode_lock:
             return list(self.tx_invs_received.keys())