Retain Content Tagger 'Tagathon participant'

We have a Rake task for removing permissions from non-GDS users, which
will be run once to rectify permissions having been inappropriately
granted before we tightened up the feature that allows delegation of
granting permissions

We've decided not to remove the 'Tagathon participant' permission, so
this updates the Rake task in preparation for running it

lib/tasks/permissions.rake

@@ -137,7 +137,6 @@ namespace :permissions do
       { application_name: "Content Data", name: "view_email_subs" },
       { application_name: "Content Data", name: "view_siteimprove" },
       { application_name: "Content Tagger", name: "GDS Editor" },
-      { application_name: "Content Tagger", name: "Tagathon participant" },
       { application_name: "Content Tagger", name: "Unreleased feature" },
       { application_name: "Manuals Publisher", name: "gds_editor" },
       { application_name: "Specialist publisher", name: "gds_editor" },

test/lib/tasks/permissions_test.rb

@@ -129,7 +129,7 @@ class PermissionsTest < ActiveSupport::TestCase
       )
       @content_tagger = application_with_revoke_and_retain_list(
         name: "Content Tagger",
-        non_signin_permissions_to_revoke: ["GDS Editor", "Tagathon participant", "Unreleased feature"],
+        non_signin_permissions_to_revoke: ["GDS Editor", "Unreleased feature"],
         retain_non_signin_permission: true,
       )
       @manuals_publisher = application_with_revoke_and_retain_list(name: "Manuals Publisher", non_signin_permissions_to_revoke: %w[gds_editor])