fix: Incorrect hovered items in tooltips

[michael-s-molina]

SUMMARY

This PR fixes an issue with incorrect hovered items in tooltips. The problem was that the algorithm was not considering that some dimension/metric combinations might result in series with missing data points.

Fixes https://github.com/apache/superset/issues/29565 Fixes https://github.com/apache/superset/issues/30045

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

https://github.com/user-attachments/assets/cdc73641-4e2b-4d6d-8ca8-0d15a1bb00a9

https://github.com/user-attachments/assets/b3454e0e-d6f1-4605-ac70-99bc9bc4c6ca

TESTING INSTRUCTIONS

Check the original issues for instructions.

ADDITIONAL INFORMATION

• [ ] Has associated issue:
• [ ] Required feature flags:
• [ ] Changes UI
• [ ] Includes DB Migration (follow approval process in SIP-59)
  • [ ] Migration is atomic, supports rollback & is backwards-compatible
  • [ ] Confirm DB migration upgrade and downgrade tested
  • [ ] Runtime estimates and downtime expectations provided
• [ ] Introduces new feature or API
• [ ] Removes existing feature or API