fix: handle burn chain flapping

[obycode]

This test (from Jude) can reproduce the problematic behavior when the burnchain flaps between two branches.

• We get blocks at height 211 - 213
• Then we get a fork, with different blocks at 211-213, as well as 214 and 215.
• We then flap back to the original fork, so it goes back to the common ancestor, 210, and tries to download 211-215
• When it gets block 211, it is already in the database, so it fails, cancelling the download of the rest of the blocks, leaving 214 and 215 in this branch not stored
• Then we try to store 216, but its parent 215 is not stored yet, so we cannot continue.

The fix for this is to ignore attempts to store duplicate blocks.

Description

Applicable issues

• fixes #

Additional info (benefits, drawbacks, caveats)

Checklist

• Test coverage for new or modified code paths
• Changelog is updated
• Required documentation changes (e.g., docs/rpc/openapi.yaml and rpc-endpoints.md for v2 endpoints, event-dispatcher.md for new events)
• New clarity functions have corresponding PR in clarity-benchmarking repo
• New integration test(s) added to bitcoin-tests.yml

[obycode]

@jcnelson I couldn't come up with a good reason why we couldn't just ignore the duplicate entry. Let me know if you see any potential problems from this.

[codecov]

Codecov Report

Attention: Patch coverage is 6.33803% with 133 lines in your changes are missing coverage. Please review.

Project coverage is 82.31%. Comparing base (0ccffa8) to head (be97a0b).

Files	Patch %	Lines
testnet/stacks-node/src/tests/neon_integrations.rs	2.77%	105 Missing ⚠️
testnet/stacks-node/src/tests/bitcoin_regtest.rs	0.00%	24 Missing ⚠️
stackslib/src/burnchains/db.rs	71.42%	2 Missing ⚠️
stackslib/src/burnchains/bitcoin/indexer.rs	50.00%	1 Missing ⚠️
stackslib/src/chainstate/coordinator/mod.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4563      +/-   ##
===========================================
+ Coverage    82.20%   82.31%   +0.11%     
===========================================
  Files          404      404              
  Lines       293057   293191     +134     
===========================================
+ Hits        240909   241350     +441     
+ Misses       52148    51841     -307     

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[jcnelson]

Can you actually base this on develop? We'd want to test this prior to shipping it in a release. We'll also want this merged into next ASAP because we'll definitely hit it in 2.5 testnet.

[obycode]

Heads up: I will reapply these changes on develop and force push in a few minutes.

[kantai]

LGTM -- just a few comments

[jcnelson]

LGTM. Just make sure CI passes 🙏

[obycode]

Hmm, the new tests failed with Failed starting bitcoind: (). Is there something else that needs to be added for the CI setup? It works locally.

[kantai]

Not that I know of, but we might get a better error from CI with this map_err removed (since you added Debug to the error anyways):

    btcd_controller
        .start_bitcoind()
        .map_err(|_e| ())

[jcnelson]

Approving for now, but we need to get that CI test working