Fix aapt2 feature split package name generation

Before flattening the resource table of a feature split, if the package
name of the feature split is the same as the base package name, the
split name is appended to the end of the feature's package name.

A bug was causing the rewritten package name to not be applied to the
feature package which resulted in the feature split being flattened
under the same package name as the base.

Bug: 184034454
Test: `m CtsSplitAppFeatureWarm_v23` && `aapt2 dump resources`
      to observe that package name is correct
Change-Id: I0a0ac57764f599c4dd05326a222056a3c52a4ae3