Fix panic in WorkerDeploymentSuite (#9505)

## What changed?
WISOTT

## Why?
Panics after the sub test finished were causing failures and CI issues

## How did you test it?
- [ ] built
- [ ] run locally and tested manually
- [ ] covered by existing tests
- [ ] added new unit test(s)
- [ ] added new functional test(s)

## Potential risks
Test only

tests/worker_deployment_test.go

@@ -2070,8 +2070,22 @@ func (s *WorkerDeploymentSuite) TestConcurrentPollers_DifferentTaskQueues_SameVe
 	tv := testvars.New(s)
 
 	tqs := 10
+	// Start all pollers concurrently (pollFromDeployment has no assertions, so it's safe to call from goroutines)
 	for i := range tqs {
-		go s.startVersionWorkflow(ctx, tv.WithTaskQueueNumber(i))
+		go s.pollFromDeployment(ctx, tv.WithTaskQueueNumber(i))
+	}
+	// Wait for all version workflows to appear (must run in the test goroutine due to assertions)
+	for i := range tqs {
+		tvI := tv.WithTaskQueueNumber(i)
+		s.EventuallyWithT(func(t *assert.CollectT) {
+			a := require.New(t)
+			resp, err := s.FrontendClient().DescribeWorkerDeploymentVersion(ctx, &workflowservice.DescribeWorkerDeploymentVersionRequest{
+				Namespace: s.Namespace().String(),
+				Version:   tvI.DeploymentVersionString(),
+			})
+			a.NoError(err)
+			a.Equal(tvI.ExternalDeploymentVersion(), resp.GetWorkerDeploymentVersionInfo().GetDeploymentVersion())
+		}, time.Minute, time.Second)
 	}
 
 	// set this version as current version