(Docs clarification) Unprotected default branch is switched to protected after import

Summary

When a project with an unprotected default branch is imported, the target project makes the default branch protected.

Steps to reproduce

1. Create a group with a project
2. Make the default branch of the project unprotected
3. Using direct transfer, import the group to a new target

Example Project

Source: https://gitlab.com/dchevalier-playground/unprotected-branch-project/-/branches

Target: https://gitlab.com/group-import-testing-2/dchevalier-playground1/unprotected-branch-project/-/branches

What is the current bug behavior?

The default branch in the target is switched to protected.

What is the expected correct behavior?

The default branch should remain the same as the source and be unprotected.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes