[Testing] Fix for flaky UITests in CI - 3

[TamilarasanSF4853]

This pull request improves the reliability and accuracy of UI tests by addressing test flakiness, enhancing assertions, and refining test logic. The main focus is on making tests more robust across different platforms (especially in CI environments) and ensuring UI behavior is correctly validated.

Test reliability improvements:

• Added retry logic for drag-and-drop actions in GesturesSenderIsView() on Mac Catalyst to reduce test flakiness in CI environments.
• Extended double-tap retry logic in TapThenDoubleTap() to both Android and iOS platforms, not just Android, to handle potential flakiness.

Test accuracy and validation enhancements:

• Improved ModalPageMarginCorrectAfterKeyboardOpens() by capturing and asserting the position of an Entry before and after keyboard appearance/dismissal, ensuring the UI remains visible and returns to its original state.
• Updated TextInEditorShouldScroll() to use a more precise scroll command (ScrollStrategy.Gesture with withInertia: false), improving test consistency.

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