Follow-up from "growth team refinement automation"

This is a follow-up issue to apply suggested improvements to the growth team refinement automation.

@nao.hashizume suggested:

suggestion (non-blocking): What do you think about separating these responsibilities into smaller methods such as unique_reactions_count or calculate_reactions_count?

Context: !2081 (comment 1323550992)

This issue also covers work on adding more applicable conditions to the add_thread_on_refinement processor.