Rename final matrix subgroup labels to Subgroups.1, Subgroups.2, ...

[mhurtado13]

Request

Rename subgroup labels in the final matrix.

Current behavior

Subgroup names follow an iteration-based naming pattern.

Expected behavior

Use pure subgroup naming in the final matrix:

• Subgroups.1
• Subgroups.2
• Subgroups.3
• etc.

Notes

This change should apply specifically to the subgroup labels in the final matrix output.

[mhurtado13]

Once updated, check for functions that use information about iteration and update them to avoid breaking