Function to determine whether a Managed Alert with the same AlertText and
SourceConfigName as the supplied pAlertRequest has been created
within the previous pSeconds seconds.
If such a Managed Alert does exist, the ID of the Managed Alert is returned.
If pLogUpdate is true, then this function will assume that a new
ManagedAlert will NOT be created and will log an update to the existing
ManagedAlert to indicate that the alert has reoccurred.
Note that the IsRecentManagedAlert() function in Ens.Alerting.Rule.FunctionSet
is a thin wrapper around this method, so care should be taken to maintain compatibility.