Merge bitcoin/bitcoin#27232: Use string interpolation for default value of -listen

5c938e7 Use string interpolation for default value of -listen (ekzyis)

Pull request description:

  This is a refactoring change. So I have read the following and will try to answer why this change should be accepted

  > * Refactoring changes are only accepted if they are required for a feature or
    bug fix or **_otherwise improve developer experience significantly_**. For example,
    most "code style" refactoring changes require a thorough explanation why they
    are useful, what downsides they have and why they *significantly* improve
    developer experience or avoid serious programming bugs. Note that code style
    is often a subjective matter. Unless they are explicitly mentioned to be
    preferred in the [developer notes](/doc/developer-notes.md), stylistic code
    changes are usually rejected.

  I have noticed in bitcoin/bitcoin#26899 (comment) that the helper message for `-listen` does not use string interpolation.

  That confused me and I wasn't sure what the reasons for that are. So it could be argued this confusion (by possibly many people in the past and in the future) may already be enough to accept this change.

  However, not accepting this means that if `DEFAULT_LISTEN` is ever changed, this helper message will still use the old value (however unlikely that may be).

  Therefore, this PR makes the helper message consistent with how other helper messages are implemented (using string interpolation) which leads to less confusion and prevents possibly wrong documentation in the future.

ACKs for top commit:
  stratospher:
    ACK 5c938e7.
  vasild:
    ACK 5c938e7
  kristapsk:
    cr utACK 5c938e7

Tree-SHA512: 8905f548ff399967966e67b29962821c28fd2620ff788c2b2bdfd088bbca75457dc63e933ad1985f93580508a65b91930fe4b2d97a2e0a7d83a3748b9ea2c26f

Author: fanquake

src/init.cpp

@@ -477,7 +477,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-externalip=<ip>", "Specify your own public address", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-fixedseeds", strprintf("Allow fixed seeds if DNS seeds don't provide peers (default: %u)", DEFAULT_FIXEDSEEDS), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-forcednsseed", strprintf("Always query for peer addresses via DNS lookup (default: %u)", DEFAULT_FORCEDNSSEED), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
-    argsman.AddArg("-listen", "Accept connections from outside (default: 1 if no -proxy or -connect)", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
+    argsman.AddArg("-listen", strprintf("Accept connections from outside (default: %u if no -proxy or -connect)", DEFAULT_LISTEN), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-listenonion", strprintf("Automatically create Tor onion service (default: %d)", DEFAULT_LISTEN_ONION), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-maxconnections=<n>", strprintf("Maintain at most <n> connections to peers (default: %u). This limit does not apply to connections manually added via -addnode or the addnode RPC, which have a separate limit of %u.", DEFAULT_MAX_PEER_CONNECTIONS, MAX_ADDNODE_CONNECTIONS), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-maxreceivebuffer=<n>", strprintf("Maximum per-connection receive buffer, <n>*1000 bytes (default: %u)", DEFAULT_MAXRECEIVEBUFFER), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);