Fix test of wait-for-window-on-boot if wallpaper is disabled

One of condition of the test is to verify that the visible-not-drawn
windows need to wait. But since commit 1e43150, mHasSurface becomes
the criteria of visible window (WindowState#isVisible). So the test
only relied on wallpaper window to pass.

Because config_enableWallpaperService may be false on car product.
That causes the test fails. This change correct the invisible testing
window to restore the original test purpose. So another non-wallpaper
window can take effect to pass the verification.

Bug: 169904362
Bug: 169904497
Test: DisplayContentTests# \
      testShouldWaitForSystemDecorWindowsOnBoot_OnDefaultDisplay
      testShouldWaitForSystemDecorWindowsOnBoot_OnSecondaryDisplay
Change-Id: I5bf3efc82fd600946114b31d921cc5097743393f

services/tests/wmtests/src/com/android/server/wm/DisplayContentTests.java

@@ -526,7 +526,8 @@ public class DisplayContentTests extends WindowTestsBase {
         for (int i = 0; i < types.length; i++) {
             final int type = types[i];
             windows[i] = createWindow(null /* parent */, type, displayContent, "window-" + type);
-            windows[i].mHasSurface = false;
+            windows[i].setHasSurface(true);
+            windows[i].mWinAnimator.mDrawState = WindowStateAnimator.DRAW_PENDING;
         }
         return windows;
     }