tetragon: Fix delayed sensor unblock code

The delayed sensor is used in TestPolicyListingWhileLoadUnload
to check on loaded sensors states with following code path.

  - one go routine is periodically listing sensors and when found
    it calls unblock on delayed sensor that sends data on sensor's
    channel

  - another go routine is adding sensor and calls Load on delayed
    sensor to receive data from the sensors channel

Currently the test can fail in delayed sensor's unblock if the
receiving side is not ready yet, which is completely ok, because
sensor is first added in the collections and only after the Load
method is called.

Instead of failing immediately adding 10 seconds timer on
delayed sensor's unblock select.

Fixes: #2576
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

pkg/sensors/delayed_sensor_test.go

@@ -66,7 +66,7 @@ func (tds *TestDelayedSensor) Destroy() {
 func (tds *TestDelayedSensor) unblock(t *testing.T) {
 	select {
 	case tds.ch <- struct{}{}:
-	default:
+	case <-time.After(10 * time.Second):
 		t.Fatalf("unblocked failed: channel does not seem to be empty")
 	}