[signer] Ignore block proposals that are older than a certain amount and just drop with a warning

[jferrant]

If a signer has fallen behind for one reason or another and its event queue starts building up with block proposals, these proposals can become incredibly old and posting a block response does not even make sense to send. Just drop them with a warning.

First add a configurable timeout value to signers for ignoring proposals that exceed this timeout (See stacks-core/stacks-signer/src/config.rs)
Next, give it a default value of 10 mins (We can always change this default later if we find a more appropriate value).
Finally, modify handle_block_proposal to drop block_proposals with a block.header.timestamp older than a configurable value (see stacks-core/stacks-signer/src/v0/signer.rs)
Do not forget to add an integration test to testnet/stacks-node/src/tests/signer/v0 and add it to the bitcoin-tests.yml file so it runs in CI.

[Parikalp-Bhardwaj]

Hi @jferrant, To make this issue more approachable and inviting for contributors, it would be helpful to add some additional context. This can significantly lower the barrier to entry for developers like me, who want to contribute but may not be familiar with the codebase.

[jferrant]

Hi @jferrant, To make this issue more approachable and inviting for contributors, it would be helpful to add some additional context. This can significantly lower the barrier to entry for developers like me, who want to contribute but may not be familiar with the codebase.

Sure :) Have edited the description!

[jferrant]

Related to: #5439