libhwui: AnimatedImageThread fix 'UAF' nits

nits from UAF CL:
- we don't need to be careful about destroying this thread
- overly verbose return

Bug: 186468053
Test: N/A
Change-Id: I96b3c5b038529341381865cbd5784ac54ba2fc9e

libs/hwui/hwui/AnimatedImageThread.cpp

@@ -22,12 +22,12 @@ namespace android {
 namespace uirenderer {
 
 AnimatedImageThread& AnimatedImageThread::getInstance() {
-    [[clang::no_destroy]] static sp<AnimatedImageThread> sInstance = []() {
+    static sp<AnimatedImageThread> sInstance = []() {
         sp<AnimatedImageThread> thread = sp<AnimatedImageThread>::make();
         thread->start("AnimatedImageThread");
         return thread;
     }();
-    return *sInstance.get();
+    return *sInstance;
 }
 
 AnimatedImageThread::AnimatedImageThread() {