Update Dockerfile.ci (#12988)

Fix permission issue in Azure DevOps when running the script install_mysql.sh, which prevents the build to succeed

/bin/bash: ./scripts/docker/install_mysql.sh: Permission denied
The command '/bin/bash -o pipefail -e -u -x -c ./scripts/docker/install_mysql.sh dev' returned a non-zero code: 126
##[error]The command '/bin/bash -o pipefail -e -u -x -c ./scripts/docker/install_mysql.sh dev' returned a non-zero code: 126
##[error]The process '/usr/bin/docker' failed with exit code 126

Dockerfile.ci

@@ -107,7 +107,9 @@ RUN mkdir -pv /usr/share/man/man1 \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
-COPY scripts/docker scripts/docker
+COPY scripts/docker /scripts/docker
+# fix permission issue in Azure DevOps when running the script
+RUN chmod a+x /scripts/docker/install_mysql.sh
 RUN ./scripts/docker/install_mysql.sh dev
 
 RUN adduser airflow \