Follow up from Prohibit non admin writes to system spaces: resolve naming and predicate check

Summary

• fix: follow up resolve naming and predicate check

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• Follow-up for https://git.picodata.io/picodata/picodata/picodata/-/merge_requests/1213

• Cherry-pick to: none

• Docs follow-up: https://git.picodata.io/picodata/picodata/docs/-/issues/338

• See also #402 (closed)