[State Sync] Add a new alert for state sync lag and tweak a config.

[JoshLind]

Description

This PR makes two small tweaks to state sync:

1. It adds an alert for state sync when the node is lagging more than 1 million versions behind head. We might want to tweak this in the future based on how often it fires, but let's start here.
2. It increases the num_versions_to_skip_snapshot_sync in the state sync config.

Test Plan

Existing infrastructure.

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This change is