Change "could not find class" to warning

Otherwise its too spammy during build.

Bug: 34929159
Bug: 34927277
Test: test-art-host

Change-Id: I94ab0ad4e3d4b8f4817c6ddadafa2576b415c746
diff --git a/profman/profman.cc b/profman/profman.cc
index a99a0ea..871967d 100644
--- a/profman/profman.cc
+++ b/profman/profman.cc
@@ -642,7 +642,7 @@
 
     ProfileMethodInfo::ProfileClassReference class_ref;
     if (!FindClass(dex_files, klass, &class_ref)) {
-      LOG(ERROR) << "Could not find class: " << klass;
+      LOG(WARNING) << "Could not find class: " << klass;
       return false;
     }