Revert "Migrate ENABLE_GRID_ONLY_OVERVIEW to aconfig flag"

This reverts commit 6f264a927b.

Reason for revert: Keeping old flag system so we can test in Tapl tests (b/283246928)
Bug: 270397206

Change-Id: I3e6364ebac8018facc3b22e510615735299a3dad

src/com/android/launcher3/DeviceProfile.java

@@ -1761,7 +1761,7 @@ public class DeviceProfile {
 
     /** Gets the space that the overview actions will take, including bottom margin. */
     public int getOverviewActionsClaimedSpace() {
-        int overviewActionsSpace = isTablet && Flags.enableGridOnlyOverview()
+        int overviewActionsSpace = isTablet && FeatureFlags.enableGridOnlyOverview()
                 ? 0
                 : (overviewActionsTopMarginPx + overviewActionsHeight);
         return overviewActionsSpace + getOverviewActionsClaimedSpaceBelow();