feat(scheduler): gracefully shutdown (#1951)

wait for workers to finish before exiting

should fix tests reporting they couldn't remove rootDir because it's being
written by tasks

Signed-off-by: Petu Eusebiu <peusebiu@cisco.com>

pkg/extensions/sync/sync_test.go

@@ -1883,9 +1883,6 @@ func TestConfigReloader(t *testing.T) {
 		destConfig.Log.Output = logFile.Name()
 
 		dctlr := api.NewController(destConfig)
-		dcm := test.NewControllerManager(dctlr)
-
-		defer dcm.StopServer()
 
 		//nolint: dupl
 		Convey("Reload config without sync", func() {
@@ -1927,6 +1924,8 @@ func TestConfigReloader(t *testing.T) {
 				time.Sleep(100 * time.Millisecond)
 			}
 
+			defer dctlr.Shutdown()
+
 			// let it sync
 			time.Sleep(3 * time.Second)
 
@@ -2075,6 +2074,8 @@ func TestConfigReloader(t *testing.T) {
 				time.Sleep(100 * time.Millisecond)
 			}
 
+			defer dctlr.Shutdown()
+
 			// let it sync
 			time.Sleep(3 * time.Second)