SERVER-136162 disabled the ListIndexesAlwaysIncludesSimpleCollation feature flag and as part of this is was also added to fully_disabled_feature_flags.yml.

We should determine if re-enabling that feature flag is viable and:

• If it's viable, remove it from fully_disabled_feature_flags.yml and fix any fallout.
• If it's not viable, remove the feature flag from the code base and propose a different design to fix the problem described in SERVER-89953.
  • IMPORTANT: Be mindful we may need to keep the compatibility shim "normalizeIndexSpecsFromListIndexes" until 10.0 is released, to deal with eg. mixed 9.0.2 - 9.x.x binary.
  • IMPORTANT: Ensure all usages of --setParameter featureFlagListIndexesAlwaysIncludesSimpleCollation=false in mongods have been removed from the Atlas fleet.
  • Remove all TODOs associated to this ticket SERVER-136165 from the code base.