[22650] Fix GitHub protected branches importer

What does this MR do and why?

This MR fixes Preserve branch protection status when importing from GitHub related functionality.

GIVEN I'm importing repository from GitHub to GitLab
AND I'm not an administrator of this repository
WHEN importer processes protected branches step
EXPECTED RESULT:
it skips all branch settings one-by-one as we haven't access to repo security info
ACTUAL RESULT:
it fails on try to fetch branch protection settings

How to set up and validate locally

Try to import any repository where you're not an administrator.

MR acceptance checklist

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