Reduce app image log spam

Change to VLOG or file exists.

Bug: 26782386
Bug: 22858531
Change-Id: Ic73d110d44216c2846e4ea789070bea2af8043a3
diff --git a/runtime/oat_file_assistant.cc b/runtime/oat_file_assistant.cc
index 2bd5c76..a8f84a2 100644
--- a/runtime/oat_file_assistant.cc
+++ b/runtime/oat_file_assistant.cc
@@ -1026,7 +1026,7 @@
   gc::space::ImageSpace* ret = gc::space::ImageSpace::CreateFromAppImage(art_file.c_str(),
                                                                          oat_file,
                                                                          &error_msg);
-  if (ret == nullptr) {
+  if (ret == nullptr && (VLOG_IS_ON(image) || OS::FileExists(art_file.c_str()))) {
     LOG(INFO) << "Failed to open app image " << art_file.c_str() << " " << error_msg;
   }
   return ret;