Link popover moves sideways following the caret

[talldan]

Describe the bug
The link popover moves horizontally with the caret.

To Reproduce
Steps to reproduce the behavior:

1. Add a link to a paragraph (with some reasonably long text)
2. Use the left and right cursor keys to move the caret within the link text
3. Observe that the popover moves from left to right, following the caret

Expected behavior
The popover should be positioned at the middle bottom of the formatted text

Screenshots

Additional context

• 4.1
• The desired behaviour was discussed on this issue -Can't edit an existing link using only the keyboard #8266 (comment)
• Fixing related issue Highlighted formatting in the toolbar doesn't match MCE inline boundaries #11091 could help with this (as it would be possible to use the inline boundary to position the popover)

[mtias]

This is a regression, it was fixed before.