Respond with null data when no screen lock.

Safety Center expects a response to the broadcast in this case.
The Settings app should respond with explicitely no data to Safety
Center rather than not respond.

Bug: 295845686
Test: atest LockScreenSafetySourceTest
Change-Id: Ibaa134b1f93304731f37444ab222b3dc628bae02

src/com/android/settings/safetycenter/LockScreenSafetySource.java

@@ -63,6 +63,12 @@ public final class LockScreenSafetySource {
         }
 
         if (!screenLockPreferenceDetailsUtils.isAvailable()) {
+            SafetyCenterManagerWrapper.get().setSafetySourceData(
+                    context,
+                    SAFETY_SOURCE_ID,
+                    /* safetySourceData= */ null,
+                    safetyEvent
+            );
             return;
         }