[PWGLF] Fix derived index table labels for AO2D merging

[BongHwi]

Fix index table labels in the Omega(2012) and K1 ML data models so the AO2D merger can match persisted relations to their target tables.

Changes

• Set explicit merger table labels for the Omega(2012) event, track, and candidate indices.
• Apply the same fix to the K1 ML event, track, and candidate indices.
• Preserve the role suffixes for track indices.

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 0 warnings, 🔕 0 disabled