Fix default mainnet burnchain peer details

[alexjtupper]

Description

On 19th December 2024, the default burnchain peer referenced in the 'mainnet' config of the stacks-node program was taken down. As a result, stacks-node programs run with the 'mainnet' command (i.e. those using the config produced by ConfigFile::mainnet()) no longer sync.

This PR fixes the default mainnet burnchain peer details by updating them to match those in the stacks-blockchain-docker repo.

Applicable issues

(none currently open)

Additional info (benefits, drawbacks, caveats)

To confirm the current configuration doesn't work, you can inspect the DNS result (NXDOMAIN) of running:
dig bitcoin.blockstack.com

Here's the matching stacks-blockchain-docker sample config for mainnet: https://github.com/stacks-network/stacks-blockchain-docker/blob/master/conf/mainnet/Config.toml.sample#L12-L14

The stacks-blockchain-docker config works at the time of writing; confirmed using bitcoin-cli.

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

[CLAassistant]

All committers have signed the CLA.

[obycode]

Thanks for the contribution @alexjtupper! This was actually already fixed in develop in #5604, so I'm going to close this one.

[alexjtupper]

Thanks for the contribution @alexjtupper! This was actually already fixed in develop in #5604, so I'm going to close this one.

Perfect! Thanks for reviewing!