Thanks to G.L. DATA it is now possible to upgrade the default phpMyAdmin installed in the Plesk control panel under the DB WebAdmin icon. According to G.L. DATA the upgrade will work on version 7.1.x and 7.5.x of Plesk for Linux. We have been able to confirm that it definitely does run on Plesk 7.1.7 for Linux.
For more information see G.L. DATA Plesk page