profcollect: Register observers in a background thread

Test: presubmit
Bug: 223254054
Change-Id: I24af51326dfe9f69c0ee146387ccabfc9239e7c1

services/profcollect/src/com/android/server/profcollect/ProfcollectForwardingService.java

@@ -235,8 +235,11 @@ public final class ProfcollectForwardingService extends SystemService {
 
     // Event observers
     private void registerObservers() {
-        registerAppLaunchObserver();
-        registerOTAObserver();
+        BackgroundThread.get().getThreadHandler().post(
+                () -> {
+                    registerAppLaunchObserver();
+                    registerOTAObserver();
+                });
     }
 
     private final AppLaunchObserver mAppLaunchObserver = new AppLaunchObserver();