No longer require magic username for Git over HTTPS with OAuth token

See merge request !152282



Merged-by: Aboobacker MK <akarakath@gitlab.com>
Approved-by: Rohit Shambhuni <rshambhuni@gitlab.com>
Approved-by: Aboobacker MK <akarakath@gitlab.com>
Reviewed-by: Rohit Shambhuni <rshambhuni@gitlab.com>
Co-authored-by: M Hickford <mirth.hickford@gmail.com>
Co-authored-by: Jon Glassman <jglassman@gitlab.com>