Fully remove all the public-create-mail settings

Summary: Fixes T5703. These have been unused in production for a while and the new stuff seems good.

Test Plan: Mostly `grep`.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T5703

Differential Revision: https://secure.phabricator.com/D12949

src/applications/files/config/PhabricatorFilesConfigOptions.php

@@ -156,20 +156,6 @@ final class PhabricatorFilesConfigOptions
             "Set this to a valid Amazon S3 bucket to store files there. You ".
             "must also configure S3 access keys in the 'Amazon Web Services' ".
             "group.")),
-     $this->newOption(
-        'metamta.files.public-create-email',
-        'string',
-        null)
-        ->setLocked(true)
-        ->setLockedMessage(pht(
-          'This configuration is deprecated. See description for details.'))
-        ->setSummary(pht('DEPRECATED - Allow uploaded files via email.'))
-        ->setDescription(
-          pht(
-            'This config has been deprecated in favor of [[ '.
-            '/applications/view/PhabricatorFilesApplication/ | '.
-            'application settings ]], which allow for multiple email '.
-            'addresses and other functionality.')),
      $this->newOption(
         'metamta.files.subject-prefix',
         'string',