Fix OP Stack header validation / Remove snapshot from snap-synced chains

[jmederosalvarado]

Changes

• Removes snapshot from non-archive configs, for op networks that support snap sync
• Fix header validation logic for pre-bedrock block to only verify parent header matches parent hash. This can be done because bedrock block is always hardcoded in op chains, so it's enough to verify that the reverse chain hashes match from BedrockBlock to 0.
• Use OptimismPoSSwitcher that decides whether block is pre or post merge based on bedrock block number

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Documentation

Requires documentation update

• Yes
• No

Requires explanation in Release Notes

• Yes
• No

[emlautarom1]

The issue seems to be specific to OP-mainnet (I could not reproduce the issue on OP-sepolia)

[emlautarom1]

In the PR description you mention:

Removes snapshot from non-archive configs, for op networks that support snap sync

Is this still WIP?

[emlautarom1]

From where are we getting this value?

[jmederosalvarado]

that's the total difficulty at the height of bedrock block in op-mainnet

[emlautarom1]

Why is it that I see 0 in a block explorer then? https://optimism.blockscout.com/block/0xdbf6a80fef073de06add9b0d14026d6e5a86c85f6d102c36d3d8e9cf89c2afd3

[emlautarom1]

Also, does this PR supersede #7565 ?

[jmederosalvarado]

Also, does this PR supersede #7565 ?

That other PR also gets into fixes in the snapshot download plugin, there is a significant overlap though

[emlautarom1]

Seems to have fixed the issue on op-mainet so LGTM!