Set CATEGORY_UNDEFINED as default category

It's possible that there is no tag <application> in the mainfest.
Therefore, category wouldn't be set to CATEGORY_UNDEFINED properly.
Assign the proper default value for this case.

Fix: 207456733
Test: atest AndroidPackageInfoFlagBehaviorTest
Test: atest AndroidPackageParsingEquivalenceTest
Change-Id: I5fb82fea5ccdf216b5825c0c3a254d8be3666c04

core/java/android/content/pm/parsing/ParsingPackageImpl.java

@@ -334,7 +334,7 @@ public class ParsingPackageImpl implements ParsingPackage, ParsingPackageHidden,
     @DataClass.ParcelWith(ForInternedString.class)
     private String backupAgentName;
     private int banner;
-    private int category;
+    private int category = ApplicationInfo.CATEGORY_UNDEFINED;
     @Nullable
     @DataClass.ParcelWith(ForInternedString.class)
     private String classLoaderName;