Clear fake settings provider after the last test

The SettingsProvider may keep the testing values in cache
that may affect other tests.

Bug: 142046583
Test: atest DisplayRotationTests
Change-Id: Iebc77bcac9a2e48b80209fd1e8f559bac483fb3d

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

@@ -68,6 +68,7 @@ import com.android.server.statusbar.StatusBarManagerInternal;
 import com.android.server.wm.utils.WmDisplayCutout;
 
 import org.junit.After;
+import org.junit.AfterClass;
 import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -122,6 +123,12 @@ public class DisplayRotationTests {
         sMockWm.mPolicy = mock(WindowManagerPolicy.class);
     }
 
+    @AfterClass
+    public static void tearDownOnce() {
+        // Make sure the fake settings are cleared after the last test method.
+        FakeSettingsProvider.clearSettingsProvider();
+    }
+
     @Before
     public void setUp() {
         FakeSettingsProvider.clearSettingsProvider();