Revert "Add agent configtest option for use when verifying logstash config files prior to restarting the logstash service"

This reverts commit 5658d3658b45d1127f07aeb30bd3b03f0ea857ce.
Revert "Add agent configtest option for use when verifying logstash config files prior to restarting the logstash service"

This reverts commit 2c2b076129c30c9c17f8d6d5507e778c6169e407.