Subtract taskbar size from DeviceProfile#availableHeight

Normally availableHeight excludes system insets, but taskbar is added
after availableHeight is calculated. This discrepency causes some bad
calculations such as TaskView size.

Test: touch nav bar when in an app with taskbar present, ensure the
task doesn't jump due to incorrect calculation

Fixes: 179478728
Bug: 171917176
Change-Id: I16d39d3e1d9708e2a64c81b1ac24466f9567d1b9

quickstep/src/com/android/launcher3/BaseQuickstepLauncher.java

@@ -222,7 +222,7 @@ public abstract class BaseQuickstepLauncher extends Launcher
             mTaskbarController.cleanup();
             mTaskbarController = null;
         }
-        if (FeatureFlags.ENABLE_TASKBAR.get() && mDeviceProfile.isTablet) {
+        if (mDeviceProfile.isTaskbarPresent) {
             TaskbarActivityContext taskbarActivityContext = new TaskbarActivityContext(this);
             mTaskbarController = new TaskbarController(this,
                     taskbarActivityContext.getTaskbarContainerView());