Please move the qa-team to qa

qa is the canonical name of the QA team, used everywhere. There are no chances of it clashing with the login name of any DD as the 'qa' unix user already exists as a role account. Also alioth has the 'qa' team under that name.

Please rename https://salsa.debian.org/qa-team to https://salsa.debian.org/qa

/cc @qa-team