Fix EZP-23712: The content edit form moves if you put the mouse over the title

JIRA: https://jira.ez.no/browse/EZP-23712

# Description

This patch fixes this annoying bug where the fact that the technical infos on the content edit page are display changes the height of the head and makes the form to move. This was also the occasion to correctly that with CSS rather than with JS code which makes the unit easier and quicker.

# Tests

manual tests + unit tests
asynchronous tests because of a graphical effect