[Etherpad] Update secrets template

pica-etherpad/secrets/etherpad-app.secrets.example

-ETHERPAD_ADMIN_PASSWORD=password
+ETHERPAD_ADMIN_PASSWORD=password1
 ETHERPAD_DB_NAME=etherpad-lite
 ETHERPAD_DB_USER=etherpad
-ETHERPAD_DB_PASSWORD=password
+ETHERPAD_DB_PASSWORD=password2

pica-etherpad/secrets/etherpad-db.secrets.example

-MYSQL_ROOT_PASSWORD=password
-MYSQL_USER=etherpad
-MYSQL_PASSWORD=password
+MYSQL_ROOT_PASSWORD=password3
 MYSQL_DATABASE=etherpad-lite
+MYSQL_USER=etherpad
+MYSQL_PASSWORD=password2

pica-mattermost/secrets/mattermost-db.secrets.example

 MM_USERNAME=mattermost
-MM_PASSWORD=test
+MM_PASSWORD=samepassword
 MM_DBNAME=mattermost
 POSTGRES_USER=mattermost
-POSTGRES_PASSWORD=test
+POSTGRES_PASSWORD=samepassword
 POSTGRES_DB=mattermost