Revert "Fix check scheduling w/ retry_interval"

This reverts commit a51e647.

This patch causes trouble with check results received
1) passively 2) throughout the cluster. A proper patch
for setting the retry_interval on NOT-OK state changes
is required.

refs #11248
refs #11257
refs #11273

(the old issue)
refs #7287

lib/icinga/checkable-check.cpp

@@ -302,9 +302,6 @@ void Checkable::ProcessCheckResult(const CheckResult::Ptr& cr, const MessageOrig
 		UpdateFlappingStatus(stateChange);
 	is_flapping = IsFlapping();
 
-	/* update next check time on possible state changes */
-	UpdateNextCheck();
-
 	olock.Unlock();
 
 //	Log(LogDebug, "Checkable")