Reduce API calls for branch protection checks

[rarkins]

Describe the proposed change(s).

Example logs from a non-paid repo:

DEBUG: GET https://api.github.com/repos/msw-kialo/renovate-push-rebase/branches/main/protection = (code=ERR_NON_2XX_3XX_RESPONSE, statusCode=403 retryCount=0, duration=66) (branch="renovate/boto3-1.x-lockfile")
DEBUG: Endpoint: repos/msw-kialo/renovate-push-rebase/branches/main/protection, needs paid GitHub plan (branch="renovate/boto3-1.x-lockfile")
DEBUG: Branch protection: Do not have permissions to detect branch protection (branch="renovate/boto3-1.x-lockfile")

If a repo's base branch returns 4xx for branch protection:

• We should not check it for any other base branches
• We could cache this for 24 hours to avoid checking it again

Does not necessarily need to be only due to "needs GitHub plan".