feat: always broadcast a BlockResponse, even if globally accepted

[hstove]

• Closes https://github.com/stacks-network/stacks-core/issues/5451

Changes signer behavior to broadcast a BlockResponse, even if the signer has already marked the block as GloballyAccepted or GloballyRejected

[jcnelson]

I just want to make sure there's no DoS risk here. What stops the signer from broadcasting the same BlockResponse over and over forever? Do we do this only once per proposal?

[hstove]

I just want to make sure there's no DoS risk here. What stops the signer from broadcasting the same BlockResponse over and over forever? Do we do this only once per proposal?

Yes, the signer only broadcasts once per proposal. This code path is also only after the signer gets a block validation response - so any DOS vector would already be spamming the node's block validation endpoint

[jcnelson]

That's what I thought; just wanted to make sure.

[hstove]

I've updated the code to not re-broadcast if the block is LocallyAccepted or LocallyRejected. So, this PR is essentially changing the check from "if globally X, ignore" to "if locally X, ignore"