Maven virtual registry upstreams: clean up the trailing / on urls

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Work on this issue

🔥 Issue

Currently, we can create 2 upstreams with the same url (one without the trailing / and one with it).

This leads to a not optimal situation where both upstreams are targeting the same host = we could be caching artifact files twice.

🚒 Solution

• Cleanup the url on upstreams (remove the trailing /) before persisting the record.