Set deduplicate strategy to untill_executed

IssuePlacementWorker is being invoked on every issue creation.
If a project creates multiple issues in a very short time, the
IssuePlacementWorker can be invoked multiple times for the same
project. Avoid that by deduplicating the job through
untill_executed strategy.

app/workers/issue_placement_worker.rb

@@ -4,6 +4,7 @@ class IssuePlacementWorker
   include ApplicationWorker
 
   idempotent!
+  deduplicate :until_executed, including_scheduled: true
   feature_category :issue_tracking
   urgency :high
   worker_resource_boundary :cpu

spec/workers/issue_placement_worker_spec.rb

@@ -129,4 +129,9 @@ RSpec.describe IssuePlacementWorker do
       it_behaves_like 'running the issue placement worker'
     end
   end
+
+  it 'has the `until_executed` deduplicate strategy' do
+    expect(described_class.get_deduplicate_strategy).to eq(:until_executed)
+    expect(described_class.get_deduplication_options).to include({ including_scheduled: true })
+  end
 end