It's very easy to forget to add `require 'rails_helper'` at the top of every core/plugin spec file, and omissions can cause some very confusing/sporadic errors.
By setting this flag in `.rspec`, we can remove the need for `require 'rails_helper'` entirely.
In an earlier PR, we decided that we only want to block a domain if
the blocked domain in the SiteSetting is the final destination (/t/59305). That
PR used `FinalDestination#get`. `resolve` however is used several places
but blocks domains along the redirect chain when certain options are provided.
This commit changes the default options for `resolve` to not do that. Existing
users of `FinalDestination#resolve` are
- `Oneboxer#external_onebox`
- our onebox helper `fetch_html_doc`, which is used in amazon, standard embed
and youtube
- these folks already go through `Oneboxer#external_onebox` which already
blocks correctly
