Test pushing a moderately sized repo to a new project

What

An end to end test which attempts to push a large-ish repo to a new project. Potentially with different settings enabled on the project as these things like push rules or having LFS enabled can slow down this process.

Why

We shouldn't be able to break this, and have experienced performance regressions which cause pushes to time out.

Related

https://gitlab.com/gitlab-org/gitlab-ce/issues/43281#note_59133353