[FIX] ir_model: avoid records duplicates in dichotomy

When uninstalling a module, all related ir.model.data records are
unlinked, if the unlink fails, a dichotomy is performed until all
records are unlinked.

It happens that a record appears in both part of the dichotomy. In that
case, the record is deleted in the first part. When second part records
are unlinked, a crash occurs because the record cannot be found anymore.

With this commit, sets are used instead of lists to store the records
that need to be removed, avoiding duplicates in dichotomy.

closes odoo/odoo#46323

Signed-off-by: Raphael Collet (rco) <rco@openerp.com>