Absolute time picker does not respect actual time selection

[tbragin]

Repro:

• Open the Discover tab
• Expand timepicker and select a wide relative time range (e.g. last 2 years)
• Keep timepicker open, switch to Absolute
• Zoom in on a dataset by drag-and-select in Discover
• See that time range in the Absolute time picker does not reflect the actual time range in the timepicker

[tbragin]

Note, this still happens in 5.0-beta1 snapshot, but note that the update doesn't happen only when the timepicker remains open. Once you close and reopen it, the timepicker "catches up".