Remove `packageVersion` from the `source-manifest.json`

[premun]

The packageVersion attribute is used to feed into the build to create the exact build versions over again (git-info files). However, the git-info files are more complete in this respect, since they also have the OfficialBuildId.

The plan is:

• VMR-lite - Keep the parts of the git-info files that are required for source-build build to reproduce Microsoft's version numbers. Remove the rest.
• VMR-lite - Remove this field (use only the git-info files)
• VMR - Remove git-info files