Draft: Resolve ""PG::UndefinedObject: ERROR: index "index_taggings_on_taggable_id_and_taggable_type_and_context" does not exist - upgrade fail"

What does this MR do and why?

Before dropping index_taggings_on_taggable_id_and_taggable_type_and_context verify if it exists

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Related to #341650 (closed)