Remove FloatingHeaderSnapConfiguration.vsync deprecation

[Piinks]

This removes the vsync parameter from FloatingHeaderSnapConfiguration.

The replacement for which is to use SliverPersistentHeaderDelegate.vsync instead. This is not supported by dart fix.

This deprecations has expired, as laid out in flutter.dev/go/deprecations-removed-after-2-5

Part of #90287

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[flutter-dashboard]

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If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

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[goderbauer]

LGTM

[Piinks]

Verified internal customers are all migrated.

[fluttergithubbot]

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