Avoid creating potentially large empty arrays when clearing grid cache

[pepijnve]

Description

This PR adds a more efficient code path in gridConnector.ts that avoids creating potentially large Arrays in order to clear values in the grid cache. This change depends on vaadin/web-components#7808

Fixes #6648

Type of change

• Bugfix
• Feature

Checklist

• I have read the contribution guide: https://vaadin.com/docs/latest/contributing/overview
• I have added a description following the guideline.
• The issue is created in the corresponding repository and I have referenced it.
• I have added tests to ensure my change is effective and works as intended.
• New and existing tests are passing locally with my change.
• I have performed self-review and corrected misspellings.
• I have not completed some of the steps above and my pull request can be closed immediately.

Additional for Feature type of change

• Enhancement / new feature was discussed in a corresponding GitHub issue and Acceptance Criteria were created.