Odd behavior when using `EuiPopover` in tables

[cchaos]

This example just shows the sort dropdown, but the same behavior happens on any popover like multiple actions.

This example just starts in responsive layout for tables, but happens at wider widths too.

Link to gif if not showing inline

There are 3 things happening here:

1. When clicking the popover button, the page auto-scrolls back to the top.
2. The popover isn't getting the correct position until the browser's width is changed.
3. When the browser's width is widened to get out of responsive table mode, which removes the sort dropdown, the popover stays open but doesn't have anything to position against anymore, so it's in the top left.

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I consider this a blocker as this functionality can now break in current table implementations.

[cchaos]

If you need another simpler doc page to see the behavior of no. 1, it happens to pagination as well.

[chandlerprall]

Item 2 (correct position) is related to #955

[chandlerprall]

2 is caused by 1 - the scroll jumps the window to the top so there is no placement which places the popover in the viewport.

Item 1 is caused by EuiContextMenuPanel's (used by EuiTableSortMobile) tabIndex="0".