Remove display of githubUsername per request: @Humbedooh

[ShaneCurcuru]

Per the 'dooh, this attribute is no longer used, and should not be displayed. Eventually we can remove entirely.

[sebbASF]

See INFRA-25672

[clr-apache]

Maybe we should add a link from some of these to the Boxer page where the user can see the git---svn connections?

[sebbASF]

There is already a link to https://gitbox.apache.org/boxer/ on the committer page; this is so they can link their id.

AFAICT it only shows the link (if any) for the logged in user, so it is no use elsewhere.

[sebbASF]

Is there any point leaving this open, given that it conflicts with INFRA-25672?

[sebbASF]

Appears to be obsolete