I adjusted your patch a bit as it didn't apply cleanly and pushed it to https://salsa.debian.org/mariadb-team/mariadb-server/-/merge_requests/47 to replace the transitional mariadb-client-10.5 I had earlier.
Thanks for diving deep in piuparts testing for MariaDB 10.11 and for the patch! Ideally the CI itself had all the install/upgrade scenarios that are relevant. Contributions to the debian/salsa-ci.yml file are also very welcome!
