[IMP] base_import: error message on transport/HTTP failure
[IMP] base_import: error message on transport/HTTP failure

Attempt to clarify/improve error message (and avoid traceback) when
import fails due to some intermediate system e.g. memory error or
gateway timeout.

Task 38254

Closes #20627

This change is loosely related to
35d452cffbb1554c70f0acba85dfc4ef472f544c and PR #24854 in the sense
that that was an attempt to better handle transport/gateway issues
during file download.

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo