Fix overridable in certificate errors

In Chromium 63 the decision of which errors were overridable was moved
to the UI. Here we duplicate what Chrome has as their soft list of
overridable errors which should match previous behavior.

Task-number: QTBUG-66844
Change-Id: Icddff745d2323608487ecbfba4040b98c10f6e66
Reviewed-by: Michael Brüning <michael.bruning@qt.io>