phpMyAdmin: The additional features for working with linked tables have been deactivated
Solution 1:
You simply need to log out of phpMyAdmin or remove the session cookies and reload once the changes are made.
Solution 2:
Looking everywhere I ended up editing this file
/etc/dbconfig-common/phpmyadmin.conf
Nothing related to what I was triyng to do, but I found this comment
# automatically generated by the maintainer scripts of phpmyadmin
# any changes you make will be preserved, though your comments
# will be lost! to change your settings you should edit this
# file and then run "dpkg-reconfigure phpmyadmin"
So I ran dpkg-reconfigure phpmyadmin
despite the fact that it already ran at install time.
It asked me if I wanted to recreate the database, my answer was NO.
And now
$cfg['Servers'][$i]['pmadb'] ... OK
$cfg['Servers'][$i]['relation'] ... OK
General relation features: Enabled
$cfg['Servers'][$i]['table_info'] ... OK
Display Features: Enabled
$cfg['Servers'][$i]['table_coords'] ... OK
$cfg['Servers'][$i]['pdf_pages'] ... OK
Creation of PDFs: Enabled
$cfg['Servers'][$i]['column_info'] ... not OK [ Documentation ]
Displaying Column Comments: Disabled
Bookmarked SQL query: Enabled
Browser transformation: Disabled
$cfg['Servers'][$i]['history'] ... OK
SQL history: Enabled
$cfg['Servers'][$i]['designer_coords'] ... OK
Designer: Enabled
It's not an upgrade, the table is called pma_column_info
and the truth is, I don't care anymore. At least the functions I wanted now are going to work