Raise the batch size outside of sandblasting to 1000

[str4d]

Currently SYNC_BATCH_SIZE is set to 100. This is fine for scanning during the sandblasting region of the chain, but outside that we should raise the limit to 1000.

Eventually the batch size will be dynamic in number of blocks (instead based on subtree boundaries, which are related to the number of outputs which is where our size and scanning costs come from), but this is a quick intermediate step.