The total number of events in which port copy packets were
dropped by the switch at the destination port due to lack of
resources.
Note that this number is not necessarily the number of
packets dropped; it is just the number of times this
condition has been detected.
A single dropped event counter is maintained for each
portCopyDest. Thus all instances associated with a given
portCopyDest will have the same portCopyDestDropEvents
value.