added DriveThru sites as shared credentials

[mpanighetti]

• added DriveThru sites as shared credentials (confirmed firsthand that all these sites use a shared account, as they are part of the "DriveThru family of sites")

Overall Checklist

• I agree to the project's Developer Certificate of Origin
• The top-level JSON objects are sorted alphabetically
• There are no open pull requests for the same update

for shared-credentials.json

• There's evidence the domains are currently related (SSL certificates, DNS entries, valid links between sites, legal documents etc.)
• If using shared, the new group serves login pages on each of the included domains, and those login pages accept accounts from the others. (For example, we wouldn't use a shared association from google.co.il to google.com, because google.co.il redirects to accounts.google.com for sign in.)

[rmondello]

Run ruby tools/convert-shared-credential-to-legacy-format.rb --verify
  ruby tools/convert-shared-credential-to-legacy-format.rb --verify
  shell: /usr/bin/bash -e {0}
ERROR: websites-with-shared-credential-backends.json is not up-to-date. Please run this script again and commit the changes.
Error: Process completed with exit code 1.

Please run tools/convert-shared-credential-to-legacy-format.rb and commit the result of that. (Sorry about this! We should automate that somehow.)

[mpanighetti]

Thanks! Added a few more sites to the same shared credential set and ran the fixer script, should be good to test now.