Graceful fixes (#8645)

* Only attempt to kill parent once

* Apply suggestions from code review

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Add waitgroup for running servers

modules/graceful/graceful_windows.go

@@ -9,3 +9,8 @@ package graceful
 
 // This file contains shims for windows builds
 const IsChild = false
+
+// WaitForServers waits for all running servers to finish
+func WaitForServers() {
+
+}