Low: ldirectord: Fix unset failcount error

This error was noticed in the logs:

Use of uninitialized value in numeric gt (>)

The uninitialized use comes from the "_service_up" function
which tries to read an uninitialized array element "failcount"
which get only written (set > 0) in the "_service_down" function.

This patch sets failcount to 0 in the constructor to avoid
triggering the error.