Unify path regex for namespace and project

See discussion in !65489 (comment 619858116)

Hmm, it seems like this regexp is just trying to match against the namespace? I don't get why we match with .git and not with something like full_project_git_path_regex

Yes, its strange indeed. I think the reason was this commit trying to make routing compatible with group wiki. Anyway its a bit confusing now as git-over-http routing is generalized and is not in sync with the rest of project routing.

I think if we want to avoid trouble in future we need identical rules for both namespace and project regex. Like now we have this issue where namespace disallow dot now but project allows it. We can then simplify this enormous collection of regular expressions we have.

It means repository_route_regex serves for both group and project repositories now. Project allows trailing dot but namespace does not.So adding trailing dot to regex above we "fix" consistency with project regex and break consistency with namespace regex.

As a side note we discuss merging project into group (or group into project) since we aim for feature parity between those. So having both namespace and project the same rules/regex would be a necessity anyway.