bbw: Debian ci image - maintained 11.4 branch as base

Rather than the 11.1 branch that won't get any more commits.

Author: grooverdan

ci_build_images/debian.Dockerfile

@@ -5,7 +5,7 @@
 
 ARG BASE_IMAGE
 FROM "$BASE_IMAGE"
-ARG MARIADB_BRANCH=11.1
+ARG MARIADB_BRANCH=11.4
 LABEL maintainer="MariaDB Buildbot maintainers"
 ENV CARGO_NET_GIT_FETCH_WITH_CLI=true