chore: Some Line Chart Enhancements to Axes for Clarity

[dthyresson]

Line charts could use some enhancements to make chart more readable:

1. on y-axis, show the unit (sec or sec) to know what performance is measured in
2. on x-axis, chose to show date or time from ago, control tick spacing for readability
3. if using time ago, better handle unit (4500 seconds might be better in hrs, for example)