Fixed leak and removed no-shuffle tag in long_press_test.dart

[Swiftaxe]

Fixes test/gestures/long_press_test.dart of #85160

The LongPressGestureRecognizer in test 'non-allowed pointer does not inadvertently reset the recognizer' was not disposed breaking a lot of other tests.

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• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
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• I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making or feature I am adding, or Hixie said the PR is test-exempt.
• All existing and new tests are passing.

[gspencergoog]