LValue widget metric data gets summarized wrong

*tldr* Graph widgets need their metrics summarized in intervals that are not relative to the current time, lvalue widgets need their metrics summarized in intervals relative to the current time (and this is not happening).

If a graph widget's was showing values from `10:38` to `10:43` and the bucket size was in 5 minute intervals, the metric values should be summarized to these buckets: `[10:40, 10:45]`.

If an lvalue widget's was showing values from `10:38` to `10:43` and the bucket size was in 5 minute intervals, the metric values should be summarized to these buckets: `[10:38, 10:43]`. The widget is currently showing these times, but is summarizing the values similar to the way graph widgets are (the buckets aren't relative to `10:43`).