remove `maintainer_github` from all modules and templates

[matifali]

• maintainer_github should no longer be required and should be removed from all modules and templates.
• Additionally, it should be listed to ensure it is not added to any new modules and templates.
• This is causing a build bug by placing modules and templates under the wrong namespace.

Related to #132

[Parkreiner]

Side note: no work should be started on this PR until we can get the build step fully updated to drop all concept of the maintainer_github field. Part of the problems we're having is that the field was supposed to be fully deprecated/removed, but it wasn't. I'll update this issue once that work is done

[Majain004]

#245 Done