Remove usage of custom admin url on store setup or DB import

[Andrii-Antoniuk]

When we import a DB from another instance it could be having admin/url/use_custom config set to 1 since it is a good practice to move admin url from regular storefronts.

On local env this would cause issues with opening the generated admin url, since in DB there will be admin/url/use_custom flag set to true.

We need to either strip it out or change in DB or change it in env.php