Issue #169: Update unit test to disable custom metrics.

[josepico01]

• Since all metrics are enabled by default and data provider was supplied with builtin metrics only, we need to disable those custom metrics before the schedule task is executed.

[cameron1729]

Thanks @josepico01

With this patch, what would happen if a new "built in" metric was added and the execute_provider remained unchanged? I think we'd have the same problem right?

I think a better approach may be to disable all metrics at the beginning of test_execute - and this may have been the original intention because there's a line in the loop that explicitly enables the metric. By doing it this way, all metrics are gauranteed to be disabled, except the ones provided by execute_provider.

What do you think?