feat:splitstore:Update config default value

[ZenGround0]

Related Issues

#10580

Proposed Changes

Set splitstore max space config as default

Additional Info

This config value will bound total lotus hotstore space during moves between 500 - 650 GiB by default
Reviewers should advise if this is too small / the resources needed for frequent moves is expected to be too burdensome
We should probably land this alongside #10392 so that more frequent moving GCs have less impact on chain sync

Checklist

Before you mark the PR ready for review, please make sure that:

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• PR title is in the form of of <PR type>: <area>: <change being made>
  • example: fix: mempool: Introduce a cache for valid signatures
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• New features have usage guidelines and / or documentation updates in
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• Tests exist for new functionality or change in behavior
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