[29.x] Backports #33474

1. 
   fanquake commented at 2:41 pm on September 24, 2025: member

   Backports:

   • #33446
2. test: add block 2016 to mock mainnet

   The next commit requires an additional mainnet block which changes the difficulty.
   
   Also fix a few minor mistakes in the test (suite):
   - rename the create_coinbase retarger_period argument to halving_period. Before bitcoin#31583 this was hardcoded for regtest where these values are the same.
   - drop unused fees argument from mine helper
   
   Finally the CPU miner instructions for generating the alternative mainnet chain are expanded.
   
   Github-Pull: #33446
   Rebased-From: 4c3c1f42cf705e039751395799240da33ca969bd

   118abf4c30
3. rpc: fix getblock(header) returns target for tip

   A target field was added to the getblock and getblockheader RPC calls in bitcoin#31583, but it mistakingly always used the tip value.
   
   Because regtest does not have difficulty adjustment, a test is added for mainnet instead.
   
   Github-Pull: #33446
   Rebased-From: bf7996cbc3becf329d8b1cd2f1007fec9b3a3188

   22ab141243
4. doc: update release notes for 29.x 94819c25f0
5. fanquake added this to the milestone 29.2 on Sep 24, 2025
6. DrahtBot added the label Backport on Sep 24, 2025
7. 
   DrahtBot commented at 2:41 pm on September 24, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33474.

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Contributors
fanquake DrahtBot

Labels
Backport

Milestone
29.2