[FIX] core: ignore imported modules when loading registry

The existing code was generating misleading errors for imported Odoo
modules that could not be loaded.  Although there was a specific hack
for module 'studio_customization', imported modules were not handled
properly.  This patch adds the right condition in the SQL query in the
module that introduces imported modules.

closes odoo/odoo#105955

Signed-off-by: Vincent Schippefilt (vsc) <vsc@odoo.com>