Fixed an issue with overflow exceptions with nested lists inside a reorderable list item.

[darrenaustin]

Fixes #83224.

The issue is caused by the nested list picking up the outer scaffold top padding when it is moved to the overlay. The parent ReorderableList normally deals with that so that any nested list views won't see the padding. However, when the item is moved to the overlay, it is now a top level list and picks up the padding which causes it to overflow the size of the list item. This PR fixes this by removing any top padding from the MediaQueryData that wraps the child.

Added a new test to ensure this doesn't break again.

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• 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.

[Piinks]