Log DexManager realpath errors only in debug mode.

Test: runtest -x .../DexManagerTests.java
Bug: 33807524

(cherry picked from commit bb9ed1f3c9)

Change-Id: Ib962edf67ce7f5b9b93c9bc6855675e00e025810

services/core/java/com/android/server/pm/dex/DexManager.java

@@ -271,7 +271,11 @@ public class DexManager {
             try {
                 dataDirs.add(PackageManagerServiceUtils.realpath(new File(ai.dataDir)));
             } catch (IOException e) {
-                Slog.w(TAG, "Error to get realpath of " + ai.dataDir, e);
+                if (DEBUG) {
+                    // Verify why we're getting spam at boot for some devices.
+                    // b/33807524
+                    Slog.w(TAG, "Error to get realpath of " + ai.dataDir, e);
+                }
             }
 
         }