Reduce EnqueuerWorker lease timeout

Reduce the EnqueuerWorker lease timeout from
1 hour to 30 minutes.

app/workers/container_registry/migration/enqueuer_worker.rb

@@ -8,7 +8,7 @@ module ContainerRegistry
       include Gitlab::Utils::StrongMemoize
       include ExclusiveLeaseGuard
 
-      DEFAULT_LEASE_TIMEOUT = 1.hour.to_i.freeze
+      DEFAULT_LEASE_TIMEOUT = 30.minutes.to_i.freeze
 
       data_consistency :always
       feature_category :container_registry

spec/workers/container_registry/migration/enqueuer_worker_spec.rb

@@ -261,7 +261,7 @@ RSpec.describe ContainerRegistry::Migration::EnqueuerWorker, :aggregate_failures
       let(:lease_key) { worker.send(:lease_key) }
 
       before do
-        stub_exclusive_lease_taken(lease_key, timeout: 1.hour)
+        stub_exclusive_lease_taken(lease_key, timeout: 30.minutes)
       end
 
       it 'does not perform' do