Use PersistedTaskSnapshotData to calculate TaskView size

- Disabled variable width for running task, as PersistedTaskSnapshotData is not always up to date for current task after rotating the device

Bug: 174464656
Test: Test tablet overview with different comination of portrait/landscape wide/narrow thumbnails in portrait/landscape
Change-Id: Ifa01e72020ccaf422e3975b092462de85fa19efd