Fix GitHub import of protected branches

What does this MR do and why?

It solves GitHub importer doesn't import all protected branches

Screenshots or screen recordings

GitHub-importer-doesnt-import-all-protected-branches

How to set up and validate locally

1. Have a project with several branches on GitHub
2. On GitHub create any branch protection rules for 2 non-default branches
3. Import the project to GitLab
4. Go to project -> Settings -> Repository -> Protected branches
5. Look at the list of protected branches
6. Ensure all the protected branches are present in the list

MR acceptance checklist

• I have evaluated the MR acceptance checklist for this MR.