ProxyBuilder::build creates incorrect @see link in class PHPDoc

Changed @see link to correct namespace.

Test failures

But this seems like a good issue for new users.

We, the mentoring team, are triaging issues for first time contributors at DrupalCon Lille and I think this is a good issue for the contribution day.
We are reserving this issue so please don't work on this issue if you are not at DrupalCon Lille. You can continue the work when the event is over.

Postponed on the possible deprecation of ProxyBuilder in 📌 Deprecate Drupal ProxyBuilder in favor of Symfony lazy services Closed: won't fix .

Unpostponing, the mentioned issue is more complicated as expected and will take a while.

Duplicate of 🐛 ProxyBuilder generates incorrect @see reference Active