Revert "event: fix Resubscribe deadlock when unsubscribing after inner sub ends (#28359)"

This reverts commit 3a1adc8a6e.

event/subscription.go

@@ -120,7 +120,7 @@ func ResubscribeErr(backoffMax time.Duration, fn ResubscribeErrFunc) Subscriptio
 		backoffMax: backoffMax,
 		fn:         fn,
 		err:        make(chan error),
-		unsub:      make(chan struct{}, 1),
+		unsub:      make(chan struct{}),
 	}
 	go s.loop()
 	return s

event/subscription_test.go

@@ -154,27 +154,3 @@ func TestResubscribeWithErrorHandler(t *testing.T) {
 		t.Fatalf("unexpected subscription errors %v, want %v", subErrs, expectedSubErrs)
 	}
 }
-
-func TestResubscribeWithCompletedSubscription(t *testing.T) {
-	t.Parallel()
-
-	quitProducerAck := make(chan struct{})
-	quitProducer := make(chan struct{})
-
-	sub := ResubscribeErr(100*time.Millisecond, func(ctx context.Context, lastErr error) (Subscription, error) {
-		return NewSubscription(func(unsubscribed <-chan struct{}) error {
-			select {
-			case <-quitProducer:
-				quitProducerAck <- struct{}{}
-				return nil
-			case <-unsubscribed:
-				return nil
-			}
-		}), nil
-	})
-
-	// Ensure producer has started and exited before Unsubscribe
-	close(quitProducer)
-	<-quitProducerAck
-	sub.Unsubscribe()
-}