system_tables.md: update _pico_tier

Изменения

Address changes from picodata!972 (merged)

Версия: Picodata 24.3.0-191-g5ea8e375 (picodata@5ea8e375)

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• Close #247 (closed)
• Changes should be cherry-picked to 24.2: no
• Staging:
  • https://docs.binary.picodata.io/picodata/asabirov_update_pico_tier/architecture/system_tables/
  • https://docs.binary.picodata.io/picodata/asabirov_update_pico_tier/architecture/raft_failover/