Merge bitcoin/bitcoin#33453: docs: Undeprecate datacarrier and datacarriersize configuration options

451ba9ada4 datacarrier: Undeprecate configuration option (Anthony Towns)

Pull request description:

  Removes the deprecation for the `datacarrier` and `datacarriersize` options by reverting commit 0b4048c733 from https://github.com/bitcoin/bitcoin/pull/32406

  **Many current Bitcoin Core users want to continue using this option**
  This statement is based on public postings from many Bitcoin Core users and not a formal survey. AJ Towns’ observation from [#32406](0b4048c733 (r2084024874)) that “_for now there seem to be a bunch of users who like the option_” has only become more apparent in the months since.

  **The deprecation intent is unclear to users**
  This echo’s Ava Chow’s comment from #32714 that “_IMO we should not have removal warnings if there is no current plan to actually remove them._” In months since that comment, partially due to increased feedback from Bitcoin Core users wanting to keep this option, there is even less likelihood of a near term plan to remove these options. That leaves Bitcoin Core users in an unclear situation: the option could be removed in the next version or perhaps never. Removing the deprecation gives clarity for their planning purposes. Deprecating the option in the future, preferably with a removal schedule to better inform users, would still be possible.

  **Minimal downsides to removing deprecation**
  As a best practice, Bitcoin Core has avoided an option when the developers cannot articulate when they should be used. There is non-zero maintenance cost to keeping this code around (although leaving the options deprecated for a long time has the same effect). “Don’t offer users footguns” is also a good principle, but with this option, there seems to be only small impacts that can quickly be remedied by changing the option value by Bitcoin Core users. There already exist in Bitcoin Core more potentially-user-harmful options/values than what datacarrier might cause.

ACKs for top commit:
  ajtowns:
    ACK 451ba9ada4
  darosior:
    That said, certain users care strongly about using those options. In these conditions, i do not see the project removing the option anytime soon. Therefore i think it's technically incorrect (and confusing) to mark it as deprecated. utACK 451ba9ada4 on removing the deprecation.
  instagibbs:
    crACK 451ba9ada4
  Raimo33:
    ACK 451ba9ada4
  Ademan:
    utACK 451ba9a
  ryanofsky:
    Code review ACK 451ba9ada4
  marcofleon:
    ACK 451ba9ada4
  achow101:
    ACK 451ba9ada4
  moonsettler:
    ACK 451ba9ada4
  ismaelsadeeq:
    utACK 451ba9ada4 🛰️
  jonatack:
    ACK 451ba9ada4
  Zero-1729:
    crACK 451ba9ada4
  vasild:
    ACK 451ba9ada4

Tree-SHA512: b83fc509f5dd820976596e1ae9fb69a22ada567e0e0ac88da5fc5e940a46d8894b40cc70c3eff2cbdabd4da5ec913f0d18c1632fc906f210b308855868410699

test/functional/mempool_datacarrier.py

@@ -100,17 +100,5 @@ class DataCarrierTest(BitcoinTestFramework):
         self.test_null_data_transaction(node=self.nodes[2], data=one_byte, success=True)
         self.test_null_data_transaction(node=self.nodes[3], data=one_byte, success=False)
 
-        # Clean shutdown boilerplate due to deprecation
-        self.expected_stderr = [
-            "",  # node 0 has no deprecated options
-            "Warning: Options '-datacarrier' or '-datacarriersize' are set but are marked as deprecated and are expected to be removed in a future version.",
-            "Warning: Options '-datacarrier' or '-datacarriersize' are set but are marked as deprecated and are expected to be removed in a future version.",
-            "Warning: Options '-datacarrier' or '-datacarriersize' are set but are marked as deprecated and are expected to be removed in a future version.",
-        ]
-
-        for i in range(self.num_nodes):
-            self.stop_node(i, expected_stderr=self.expected_stderr[i])
-
-
 if __name__ == '__main__':
     DataCarrierTest(__file__).main()