Skip submitting checkpoint signatures when checkpoint is already certified

[arun-koshy]

Description

During catchup in mysticeti if the validator was down for long periods of time we will see a large number of checkpoint signatures start to get backlogged and then submitted to consensus quickly after the node has caught up. This will cause the block size to increase in consensus and then a variance in the distribution of those blocks across the network leading to a round rate dip. This PR will skip submitting checkpoint signatures when checkpoint is already certified to mitigate the issue and we will look into properly handling block size variance in a separate PR

Testing

Recreated the issue and tested the fix in private-testnet

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
sui-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 28, 2024 0:41am

3 Ignored Deployments

| Name | Status | Preview | Comments | Updated (UTC) | | :--- | :----- | :------ | :------- | :------ | | **multisig-toolkit** | ⬜️ Ignored ([Inspect](https://vercel.com/mysten-labs/multisig-toolkit/GEAvAFtgHXwuPt3o5btC3CAN4AfE)) | [Visit Preview](https://multisig-toolkit-git-ak-skipchkptsigs-mysten-labs.vercel.app) | | Jun 28, 2024 0:41am | | **sui-kiosk** | ⬜️ Ignored ([Inspect](https://vercel.com/mysten-labs/sui-kiosk/3WbkuaVzA23Hp44xHPUAHLpJE1WL)) | [Visit Preview](https://sui-kiosk-git-ak-skipchkptsigs-mysten-labs.vercel.app) | | Jun 28, 2024 0:41am | | **sui-typescript-docs** | ⬜️ Ignored ([Inspect](https://vercel.com/mysten-labs/sui-typescript-docs/AVNT6h7ST3ZUpZEdkaFBPCnyyKAn)) | [Visit Preview](https://sui-typescript-docs-git-ak-skipchkptsigs-mysten-labs.vercel.app) | | Jun 28, 2024 0:41am |