[GitService::Repo] Update .git_fetch to 'find' creds
[GitService::Repo] Update .git_fetch to 'find' creds

Uses GitService::Credentials.find_for_user_and_host when looking up
credentials, and uses .uri_for_remote to also find hostname for a given
remote url.

ManageIQ/miq_bot,ManageIQ/miq_bot,ManageIQ/miq_bot,ManageIQ/miq_bot