Subtract inapplicable suppressed notifications at a later point

Without this commit, every time the NotificationTimerHandler runs it
will discard notifications that don't apply to the reason of the latest
check result. This is probably intended to clear outdated suppressed
notifications immediately when the TimePeriod resumes, but it also clears
out important ones (see the test case).

This commit fixes that by clearing out inapplicable notifications when
the timer runs the first time after the TimePeriod resumes. By that time
we can expect that no new suppressed notifications will be added and all
notifications that don't conflict with the last check-result can still be
run.

Fixes #10575

Author: jschmidt-icinga

lib/notification/notificationcomponent.cpp

@@ -81,23 +81,20 @@ void FireSuppressedNotifications(const Notification::Ptr& notification)
 		return;
 
 	int subtract = 0;
-	auto checkable (notification->GetCheckable());
-
-	for (auto type : {NotificationProblem, NotificationRecovery, NotificationFlappingStart, NotificationFlappingEnd}) {
-		if ((suppressedTypes & type) && !checkable->NotificationReasonApplies(type)) {
-			subtract |= type;
-			suppressedTypes &= ~type;
-		}
-	}
-
 	if (suppressedTypes) {
 		auto tp (notification->GetPeriod());
+		auto checkable (notification->GetCheckable());
 
 		if ((!tp || tp->IsInside(Utility::GetTime())) && !checkable->IsLikelyToBeCheckedSoon()) {
 			for (auto type : {NotificationProblem, NotificationRecovery, NotificationFlappingStart, NotificationFlappingEnd}) {
 				if (!(suppressedTypes & type) || checkable->NotificationReasonSuppressed(type))
 					continue;
 
+				if ((suppressedTypes & type) && !checkable->NotificationReasonApplies(type)) {
+					subtract |= type;
+					continue;
+				}
+
 				auto notificationName (notification->GetName());
 
 				Log(LogNotice, "NotificationComponent")