Add logging for when a row is ignored

Currently for the trigger if a row fails to be processed 5 times (for example if the user function throws an exception during invocation) then it will be "ignored" in future runs. This can be queried by looking at the Leases table to see what ones have _az_func_AttemptCount = 5, but there's no log message emitted or any other indication that a row will be ignored.

To help customers with debugging and monitoring of the health of their functions it would be useful to add a log message that is emitted when a row fails to be processed for the 5th time.