[Tooltip] customTooltip provides incorrect header value

[nickofthyme]

Describe the issue

When using the customTooltip prop on the Tooltip spec, the props passed to the custom component are incorrect providing the wrong vertical position of the cursor.

https://codesandbox.io/s/vigilant-villani-5w6xxs?file=/src/App.js

Expected behaviour

The customTooltip is provided the header for the actively hovered element.

Screenshots

Additional Context

This bug was introduced in v51.0.0 in #1782 with the addition of tooltip actions. Prior to this PR this inaccurate tooltip context would occur only when using a customTooltip with Tooltip.type set to vertical, where using follow would provide the correct context.