Fix RSpec/VerifiedDoubles cop (#25469)

spec/workers/domain_block_worker_spec.rb

@@ -9,7 +9,7 @@ describe DomainBlockWorker do
     let(:domain_block) { Fabricate(:domain_block) }
 
     it 'calls domain block service for relevant domain block' do
-      service = double(call: nil)
+      service = instance_double(BlockDomainService, call: nil)
       allow(BlockDomainService).to receive(:new).and_return(service)
       result = subject.perform(domain_block.id)