Reset wantsHighFrameRateIdle on pan gesture end

[lukas-cap]

When an in-flight spring animation is interrupted via completeAnimationsIfNeeded(), the completion block that resets wantsHighFrameRateIdle is never called. Reset the flag in pan .ended/.cancelled/.failed to ensure it doesn't remain enabled past the gesture lifecycle.

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

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Binary change

(how is our binary size impacted -- see https://github.com/microsoft/fluentui-apple/wiki/Size-Comparison)

Verification

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Visual Verification

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Pull request checklist

This PR has considered:

• Light and Dark appearances
• iOS supported versions (all major versions greater than or equal current target deployment version)
• VoiceOver and Keyboard Accessibility
• Internationalization and Right to Left layouts
• Different resolutions (1x, 2x, 3x)
• Size classes and window sizes (iPhone vs iPad, notched devices, multitasking, different window sizes, etc)
• iPad Pointer interaction
• SwiftUI consumption (validation or new demo scenarios needed)
• Objective-C exposure (provide it only if needed)

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