fix(grid): Proccess trailing vertical scroll updates after throttling - 22.0.x

[mddragnev]

Closes #17484 #17432

Description

Motivation / Context

Type of Change (check all that apply):

• Bug fix
• New functionality
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (no functional changes)
• Documentation
• Demos
• CI/CD
• Tests
• Changelog
• Skills/Agents

Component(s) / Area(s) Affected:

How Has This Been Tested?

• Unit tests
• Manual testing
• Automated e2e tests

Test Configuration:

• Angular version:
• Browser(s):
• OS:

Screenshots / Recordings

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them
• Accessibility (ARIA, keyboard navigation, focus management) has been verified

[Copilot]

Pull request overview

This PR adjusts the Grid’s vertical scroll event throttling so the final (trailing) scroll event is emitted and processed, addressing scroll desynchronization/gap issues reported when scrolling or navigating quickly through large datasets.

Changes:

• Update the scrollNotify RxJS throttle(...) operator configuration to enable { trailing: true } (while keeping leading: true) so the last scroll event in a throttled burst is handled.
• Align vertical scroll throttling behavior more closely with existing resizeNotify throttling configuration (which already uses leading + trailing).