Is your feature request related to a problem? Please describe.
Additional features needed in elastic-charts:

• DONE BarSeriesSpec needs to have a "histogram mode" for positioning ticks correctly (PR feat: add histogram mode #218)
  
  • ticks should be aligned to the starting edge of a bar and bars cannot be clustered (only stacked)
  • xDomain annotation positions should be aligned correctly (currently they snap to a band edge)
• DONE customizable tooltip content (PR feat(tooltip): add custom headerFormatter #233)
  • need to be able to add x-axis title to chart tooltip (formatter for tooltip header)
  • need to be able to add message about partial bucket to chart tooltip (additional information iff match for filter value)
• DONE in histogram mode, need to extend line annotation (PR fix(line_annotation): use scaleAndValidate for line annotations #236)
• DONE check bucket sizing in histogram mode, at some time intervals, buckets appear much larger (PR feat: add minInterval option for custom xDomain #240)
• DONE ticks in histogram mode need to be extended correctly (PR fix(ticks): fill in additional ticks for histogram #251 )
• DONE single datum tooltip bug (PR fix: position tooltip within chart with single value xScale #259)
• DONE show now line annotation in single datum yearly view (PR fix: adjust domain & range for single value histogram #265)

On the Kibana side:

• IN PROGRESS Use elastic-charts component (Replace Discover chart with elastic-charts kibana#43788)
  • Partial bucket rect annotations
  • Partial bucket custom tooltip header
  • Line annotation for current time
  • Axis ticks line up correctly for each time interval
  • Buckets render correctly for each time interval
    • check all ranges at auto interval
    • check all ranges at manually set intervals
  • On brush, fetch new data
  • styling (we will use the elastic-charts theme defaults but should check both dark & light modes)
  • fix tests [note updating with elastic-charts did not break any tests]
  • line annotation for now renders correctly
    • within chart when now is within time range
    • adjust position to make line visible when at domain edge
  • localize custom text
  • rect annotation tooltip should be formatted correctly
  • y-axis formatter
  • bug when hovering out of tooltip

Describe the solution you'd like
Use elastic-charts for the charts in Kibana Discover.

Describe alternatives you've considered

Additional context

Kibana Cross Issues
TODO

Checklist

• this request is checked against already exist requests
• every related Kibana issue is listed under Kibana Cross Issues list
• kibana cross issue tag is associated to the issue if any kibana cross issue is present