Migrate to use simplified prop merging

All components in @fluentui/react-slider should be migrated. See #18844 for additional details.

Checklist

• Remove defaultProps in useCOMPONENT
• Remove mergeProps
• Define type for slots
• (optionally) Define COMPONENTCommons type
• Update types for a component
• Update getSlots()
• Update useCOMPONENTStyles()