addons-stage.crt is the DER-encoded version of the
cas-cur-root-2024-03-12.crt file from bug 1882192, generated with:

openssl x509 -inform PEM -in /tmp/cas-cur-root-2024-03-12.crt -outform DER -out security/manager/ssl/addons-stage.crt

The four zip files are from bug 1885457, and are the same file, but
signed with the new certificate.

Differential Revision: https://phabricator.services.mozilla.com/D204706