Fixes incorrect URL for submodules that specify the remote port

[Governa]

If the repo's host is in urlPrefix, test if there is a number after the ":" and, if there is one, consider it as a port number and ignore it in the URL returned.

Fixes go-gitea/gitea#2775

[lunny]

@Governa if you could add some tests, it's better!

[bkcsoft]

What is my username is 1234 ? 🤔 [email protected]:1234/my_project.git should still validate to 1234/my_project.git