Drop User Burn Support

[8marz8]

Description

Removing UserBurnSupportOp definition and usage throughout the codebase as it's not fully implemented and used.

Applicable issues

• closes [Nakamoto] Drop user burn support #4071

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.41%. Comparing base (577b118) to head (7a83433).

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #4378      +/-   ##
==========================================
- Coverage   83.44%   83.41%   -0.03%     
==========================================
  Files         449      448       -1     
  Lines      325514   323911    -1603     
==========================================
- Hits       271632   270199    -1433     
+ Misses      53882    53712     -170     

Files	Coverage Δ
stackslib/src/burnchains/burnchain.rs	81.88% <100.00%> (+0.24%)	⬆️
stackslib/src/burnchains/tests/burnchain.rs	99.87% <100.00%> (+0.08%)	⬆️
stackslib/src/burnchains/tests/mod.rs	94.08% <100.00%> (+0.25%)	⬆️
stackslib/src/chainstate/burn/db/processing.rs	87.39% <ø> (-0.01%)	⬇️
stackslib/src/chainstate/burn/db/sortdb.rs	91.86% <100.00%> (-0.22%)	⬇️
stackslib/src/chainstate/burn/distribution.rs	95.88% <ø> (-0.95%)	⬇️
stackslib/src/chainstate/burn/mod.rs	94.44% <ø> (+0.24%)	⬆️
.../chainstate/burn/operations/leader_block_commit.rs	96.08% <ø> (ø)
.../chainstate/burn/operations/leader_key_register.rs	97.27% <ø> (ø)
stackslib/src/chainstate/burn/operations/mod.rs	62.44% <ø> (+2.83%)	⬆️
... and 18 more

... and 20 files with indirect coverage changes

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[8marz8]

@jcnelson @kantai Should "StagingUserBurnSupport" also be deleted?

[jcnelson]

LGTM. Thanks for taking care of this!

[jcnelson]

Also, yes -- feel free to remove StagingUserBurnSupport. As long as CI passes, it should be fine.

[kantai]

These changes look fine to me, but I do have a question, that's probably more for @jcnelson than @8marz8:

UserBurnSupport transactions are currently not considered for reward distribution or miner commitment distributions, however, they are parsed currently, correct? This would mean that they are included in the OpsHash and therefore ConsensusHash, meaning that any change to remove it from the OpsHash would need to be epoch-gated, right?

[kantai]

LGTM! I tested in a separate branch (because you can't test whether or not a UserBurn is parsed in this branch), and UserBurn ops are never parsed under 2.x consensus rules.