releasetools: Clean up two no-op lines that set 'ota-wipe'.

The same thing has been set in GetPackageMetadata(), so they are no-op.

Also replace an occurrence of 'OPTIONS.source_info_dict' with
source_info, which has been missed from previous clean-up CLs.

Test: Generate an A/B OTA package, and an incremental BBOTA with
      --wipe_user_data. Check the metadata.
Test: Generate a two-step incremental BBOTA successfully.
Change-Id: I4bb491cac9064d93fb86d12e617c8f38f040e01e