Resolve #3404256 "Fix mysql mariadb cnf permissions"

Related to #3404256

db/mariadb-10.3.22/Dockerfile

@@ -7,7 +7,7 @@ RUN apt-get -y update || true; \
     apt-get -y install netcat psmisc --no-install-recommends && \
     rm -rf /var/lib/apt/lists/*
 
-COPY ./conf/my.cnf /etc/mysql/conf.d/drupalci.cnf
+COPY --chmod=644 ./conf/my.cnf /etc/mysql/conf.d/drupalci.cnf
 
 USER root