Remove encrypted secrets and add registry to image name

pica-etherpad/docker-compose.yml

...variables-production/etherpad-app/ETHERPAD_ADMIN_PASSWORD

...rypted-variables-production/etherpad-app/ETHERPAD_DB_NAME

...ed-variables-production/etherpad-app/ETHERPAD_DB_PASSWORD

...rypted-variables-production/etherpad-app/ETHERPAD_DB_USER

...ariables-production/etherpad-app/MYSQL_PORT_3306_TCP_ADDR

...encrypted-variables-production/etherpad-db/MYSQL_DATABASE

...encrypted-variables-production/etherpad-db/MYSQL_PASSWORD

...pted-variables-production/etherpad-db/MYSQL_ROOT_PASSWORD

...ets/encrypted-variables-production/etherpad-db/MYSQL_USER

...ypted-variables-test/etherpad-app/ETHERPAD_ADMIN_PASSWORD

...ts/encrypted-variables-test/etherpad-app/ETHERPAD_DB_NAME

...ncrypted-variables-test/etherpad-app/ETHERPAD_DB_PASSWORD

...ts/encrypted-variables-test/etherpad-app/ETHERPAD_DB_USER

...pted-variables-test/etherpad-app/MYSQL_PORT_3306_TCP_ADDR

...crets/encrypted-variables-test/etherpad-db/MYSQL_DATABASE

...crets/encrypted-variables-test/etherpad-db/MYSQL_PASSWORD

.../encrypted-variables-test/etherpad-db/MYSQL_ROOT_PASSWORD

...d/secrets/encrypted-variables-test/etherpad-db/MYSQL_USER