Reuse the dimen of preview pager height percent

continue ag/11587711

If the value get changed, all tabs would still be consistent:
https://cs.corp.google.com/android/packages/apps/WallpaperPicker2/res/values/dimens.xml?q=preview_pager_maximum_height_ratio&g=0&l=199

Test: Manually
Bug: 157111978
Change-Id: I3440ccfc8f2db4c828dea60b5ac3f88aef4a2b13