Proper fix for order-dependent migration spec failure

What does this MR do?

First fix was !64476 (merged). That works but the proper fix is this MR.

See relevant discussion in !64476 (comment 606222319)

Related issue: #333202 (closed).

Testing

bin/rspec spec/migrations/20200728080250_replace_unique_index_on_cycle_analytics_stages_spec.rb spec/migrations/20210601073400_fix_total_stage_in_vsa_spec.rb

Validated running this command still passes (it was failing prior to the fix fix).