Fix PackageStateTest fails on Intent.getExtraIntentKeys

The test complains this method returns null. The test is to confirm the collection is returns is immutable. I don't plan to make this method returns an immutable collection, so add this method to the exception list similar to Intent.getCategories method.
Bug: 369445340
Test: atest PackageStateTest#collectionImmutability
Flag: TEST_ONLY

Change-Id: I38aac9cf86609d32014fb0a6d992fdf3dc77fe00