Add an software override (1sec) for TimeoutPropose

[teddyding]

Problem

Network experiences a ~5sec block time when a proposer is offline/severely lagging behind. This is due to the current software default, TimeoutPropose = 3s, which means that when a proposer is unavailable, we spend 3s waiting for the proposal + 0.5s for round 0 prevote/precommit, so ~3.5s more than an average block.

This software default of 3s was not conscious, and could've been updated along when timeout_commit was reduced to 500ms.

See attached block dump during a period when 2 small validators went offline, and 4% of the blocks have elevated >5sec blocks. As a result, average block time is much higher than median block time during this period:

Median block time: 1.1144995 seconds
Average block time: 1.35415654 seconds

Solution

Add a software override for TimeoutPropose to 1s. This should be more than enough for a block where proposer is present. . This reduces p99 and average block time.

This requires a coordinated upgrade to maintain synchrony among validators.

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PR checklist

• Tests written/updated
• Changelog entry added in .changelog (we use unclog to manage our changelog)
• Updated relevant documentation (docs/ or spec/) and code comments

[teddyding]

Proceeding dydxprotocol/v4-chain#1751 instead