Updated popover position to correctly address arrow buffer

[chandlerprall]

Summary

Addresses a bug @nreese found in elastic/kibana#29235

The tooltip has a whitespace buffer of 16px, and its arrow must be 4px from its edge. Nathan's super update button is less than 16px from the right side of the screen; the calculations were shifting the popover to meet the buffer but didn't properly account for the 4px needed for the arrow, which forced the popover to an undesired position.

@nreese mind building the fix and confirming it works in your Kibana branch?

Checklist

• This was checked in mobile
  - [ ] This was checked in IE11
  - [ ] This was checked in dark mode
  - [ ] Any props added have proper autodocs
  - [ ] Documentation examples were added
• A changelog entry exists and is marked appropriately
• This was checked for breaking changes and labeled appropriately
• Jest tests were updated or added to match the most common scenarios
  - [ ] This was checked against keyboard-only and screenreader scenarios
  - [ ] This required updates to Framer X components

[nreese]

lgtm
Tested changes in Kibana and now the tooltip stays on the bottom.