Allow clearing a single change id for tests usage.

Add clearOverrideForTest(changeId, packageName) to remove a single id
from package overrdies.

Bug: 147113465
Test: N/A
Change-Id: I35c6fe418abb9bc562218444878188bc393725e5

core/java/com/android/internal/compat/IPlatformCompat.aidl

@@ -172,6 +172,17 @@ interface IPlatformCompat {
      */
     boolean clearOverride(long changeId, String packageName);
 
+    /**
+     * Restores the default behaviour for the given change and app.
+     *
+     * <p>Does not kill the app; to be only used in tests.
+     *
+     * @param changeId    the ID of the change that was overridden
+     * @param packageName the app package name that was overridden
+     * @throws SecurityException if overriding changes is not permitted
+     */
+    void clearOverrideForTest(long changeId, String packageName);
+
     /**
      * Enables all compatibility changes that have enabledSinceTargetSdk ==
      * {@param targetSdkVersion} for an app, subject to the policy.

services/core/java/com/android/server/compat/PlatformCompat.java

@@ -210,6 +210,12 @@ public class PlatformCompat extends IPlatformCompat.Stub {
         return existed;
     }
 
+    @Override
+    public void clearOverrideForTest(long changeId, String packageName) {
+        checkCompatChangeOverridePermission();
+        mCompatConfig.removeOverride(changeId, packageName);
+    }
+
     @Override
     public CompatibilityChangeConfig getAppConfig(ApplicationInfo appInfo) {
         checkCompatChangeReadAndLogPermission();