Mark token encryption job as completed when there are no users

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/356874

It is an edge case, however it needs to be fixed.

Changelog: fixed

lib/gitlab/background_migration/encrypt_static_object_token.rb

@@ -52,9 +52,9 @@ module Gitlab
               WHERE cte_id = id
             SQL
           end
-
-          mark_job_as_succeeded(start_id, end_id)
         end
+
+        mark_job_as_succeeded(start_id, end_id)
       end
 
       private

spec/lib/gitlab/background_migration/encrypt_static_object_token_spec.rb

@@ -39,6 +39,14 @@ RSpec.describe Gitlab::BackgroundMigration::EncryptStaticObjectToken do
     expect(new_state[user_with_encrypted_token.id]).to match_array([nil, 'encrypted'])
   end
 
+  context 'when id range does not include existing user ids' do
+    let(:arguments) { [non_existing_record_id, non_existing_record_id.succ] }
+
+    it_behaves_like 'marks background migration job records' do
+      subject { described_class.new }
+    end
+  end
+
   private
 
   def create_user!(name:, token: nil, encrypted_token: nil)