I have implemented three graph pages ([contributors](https://github.com/go-gitea/gitea/pull/27882), [code frequency](https://github.com/go-gitea/gitea/pull/29191) and [recent commits](https://github.com/go-gitea/gitea/pull/29210)) and they have all same page title as the tab name so I decided to use same translations for them. This PR is for contributors graph. Other PR's have their own respective commits. (cherry picked from commit 39a77d92d9677b0a0049cb8696960d6d2ac052d6)
