Move test dependency from `required` to `libs`

The `required` is inherited from Make and is very vague. It's
discouraged by Android Build team to use it. But
CtsShortcutHostTestCases declares CtsBackupHostTestCases in the
`required` property, so that this change moves it to the `libs`
property, since CtsBackupHostTestCases is a runtime Java library of
CtsShortcutHostTestCases.

Bug: 243493884
Test: atest CtsShortcutHostTestCases
Change-Id: Iafee7b8cbed2b6e6648620fe817b2629c20ca8b1
1 file changed