Allow saving deprecated `import_sources`

Validation on `google_code` value in `import_sources` was enforced prior
to DB cleanup was executed. This causes issues with saving
`application_settings` on an instance, including GitLab.com that still
has `google_code` as a value in `import_sources`.

This change is an interim step before a proper DB migration is
introduced to clean up the `import_sources`.

lib/api/settings.rb

@@ -88,7 +88,7 @@ module API
       end
       optional :html_emails_enabled, type: Boolean, desc: 'By default GitLab sends emails in HTML and plain text formats so mail clients can choose what format to use. Disable this option if you only want to send emails in plain text format.'
       optional :import_sources, type: Array[String], coerce_with: Validations::Types::CommaSeparatedToArray.coerce,
-                                values: %w[github bitbucket bitbucket_server gitlab fogbugz git gitlab_project gitea manifest phabricator],
+                                values: %w[github bitbucket bitbucket_server gitlab google_code fogbugz git gitlab_project gitea manifest phabricator],
                                 desc: 'Enabled sources for code import during project creation. OmniAuth must be configured for GitHub, Bitbucket, and GitLab.com'
       optional :max_artifacts_size, type: Integer, desc: "Set the maximum file size for each job's artifacts"
       optional :max_attachment_size, type: Integer, desc: 'Maximum attachment size in MB'

lib/gitlab/import_sources.rb

@@ -15,6 +15,7 @@ module Gitlab
       ImportSource.new('bitbucket',        'Bitbucket Cloud',  Gitlab::BitbucketImport::Importer),
       ImportSource.new('bitbucket_server', 'Bitbucket Server', Gitlab::BitbucketServerImport::Importer),
       ImportSource.new('gitlab',           'GitLab.com',       Gitlab::GitlabImport::Importer),
+      ImportSource.new('google_code',      'Google Code',      nil),
       ImportSource.new('fogbugz',          'FogBugz',          Gitlab::FogbugzImport::Importer),
       ImportSource.new('git',              'Repo by URL',      nil),
       ImportSource.new('gitlab_project',   'GitLab export',    Gitlab::ImportExport::Importer),

spec/lib/gitlab/import_sources_spec.rb

@@ -11,6 +11,7 @@ RSpec.describe Gitlab::ImportSources do
           'Bitbucket Cloud'  => 'bitbucket',
           'Bitbucket Server' => 'bitbucket_server',
           'GitLab.com'       => 'gitlab',
+          'Google Code'      => 'google_code',
           'FogBugz'          => 'fogbugz',
           'Repo by URL'      => 'git',
           'GitLab export'    => 'gitlab_project',
@@ -31,6 +32,7 @@ RSpec.describe Gitlab::ImportSources do
           bitbucket
           bitbucket_server
           gitlab
+          google_code
           fogbugz
           git
           gitlab_project
@@ -67,6 +69,7 @@ RSpec.describe Gitlab::ImportSources do
       'bitbucket' => Gitlab::BitbucketImport::Importer,
       'bitbucket_server' => Gitlab::BitbucketServerImport::Importer,
       'gitlab' => Gitlab::GitlabImport::Importer,
+      'google_code' => nil,
       'fogbugz' => Gitlab::FogbugzImport::Importer,
       'git' => nil,
       'gitlab_project' => Gitlab::ImportExport::Importer,
@@ -88,6 +91,7 @@ RSpec.describe Gitlab::ImportSources do
       'bitbucket' => 'Bitbucket Cloud',
       'bitbucket_server' => 'Bitbucket Server',
       'gitlab' => 'GitLab.com',
+      'google_code' => 'Google Code',
       'fogbugz' => 'FogBugz',
       'git' => 'Repo by URL',
       'gitlab_project' => 'GitLab export',