Fix calculation of all apps recyclerview pool size of app icons

grid.numShownAllAppsColumns is the column size of all apps, whereas mNumAppsPerRow is the column size of workspace, we should use the former one to calculate num of all apps icons

Bug: 287523421
Flag: N/A
Test: Open all apps from launcher and taskbar and scroll it, Expect scorlling works without jank.
Change-Id: Ife488e5853c84f6cc94e1e9e7edae67844275439