disabling task doesn't reset state_duration

state_duration doesn't reset to -1, when task is disabled.
so the state doesn't `flip` even task is disabled then enabled

https://github.com/influxdata/kapacitor/blob/e58f95a4466663d64b623b668bd1185847d99c7a/state_tracking.go#L117.

does there have any way to reset all node state back to initial state ?
otherwise have to workaround with delete task and add task again.

Start with state_tracking.go at the linked line and trace how state_duration is handled when a task is disabled and enabled again. Reproduce the disable/enable sequence and verify that the node state returns to its initial state and can flip again; identify any existing state-related tests before making the change.

Written by the indexing model from the issue text.