Rename master to main in views placeholders
What does this MR do?
As we migrate from master to main, let's rename the branch in views as well. It's responsible to initial branch settings (application or group) and compare page:
Since these are just recommendations to a user, we can merge them in 13.12 and display
Related issue: https://gitlab.com/gitlab-org/gitlab/-/issues/323925
Edited by Igor Drozdov