fix: Insight tooltip overscrolling issue

[benjackwhite]

Problem

The tooltip can get rendered offscreen and because it is a child of the root it causes a big over-scroll.

This is partly because we changed the scroll so that the root is no longer a truly scrollable element but if a hover element is placed off screen that triggers the scroll

Changes

• Don't display the tooltip until it is first actually used (stops it flowing the DOM)
• Fix the bounds of the problematic tooltip (so that it doesn't suddenly jump from off screen when it gets displayed)

Really that tooltip needs a re-think. Lots of duplicated code everywhere but this at least fixes the issue for now

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How did you test this code?

[thmsobrmlr]

I could not replicate the original issue locally (seems there are some preconditions that I'm unaware of). Changes seem fine and I trust your reasoning.

[benjackwhite]

I could not replicate the original issue locally (seems there are some preconditions that I'm unaware of). Changes seem fine and I trust your reasoning.

You need to add a "Big number" insight to a dashboard far enough down that it is off the screen. Thats how I recreated it