winlogbeat: allow termination while attempting to open channels (#35474)

Currently, if winlogbeat is attempting to open a channel that is not
available because it is not found or there is a recoverable error, it
will loop and retry. Since signals have been sent to notification
handlers by this point, cancellation of the loop is not possible without
agreement. So add a cancellation select at the head of the retry loop to
allow termination.

CHANGELOG.next.asciidoc

@@ -206,6 +206,7 @@ automatic splitting at root level, if root level element is an array. {pull}3415
 - Move repeated channel not found errors to debug level.  {issue}35314[35314] {pull}35317[35317]
 - Fix panic due to misrepresented buffer use. {pull}35437[35437]
 - Prevent panic on closing iterators on empty channels in experimental API. {issue}33966[33966] {pull}35423[35423]
+- Allow program termination when attempting to open an absent channel. {pull}35474[35474]
 
 *Functionbeat*
 

winlogbeat/beater/eventlogger.go

@@ -136,6 +136,12 @@ func (e *eventLogger) run(
 
 runLoop:
 	for stop := false; !stop; {
+		select {
+		case <-done:
+			return
+		default:
+		}
+
 		err = api.Open(state)
 
 		switch {