add DRIVERCLASS_NAME, PROTOCOL, SUB_PROTOCOL to docker-compose.yml

These are the default values, from jdbc.properties, only added for
clarity and to make it obvious that they need to be changed e.g. for
FINERACT-762.

The different formats and naming conventions are a little bit of a mess,
but changing them now leads to backwards incompatibility, so for now
let's leave as is; possible clean up later in FINERACT-889.

docker-compose.yml

@@ -44,6 +44,9 @@ services:
       - fineractmysql
     environment:
       - JAVA_OPTS=-Djava.awt.headless=true -XX:+UseG1GC -Dfile.encoding=UTF-8
+      - DRIVERCLASS_NAME=org.drizzle.jdbc.DrizzleDriver
+      - PROTOCOL=jdbc
+      - SUB_PROTOCOL=mysql:thin
       - fineract_tenants_driver=org.drizzle.jdbc.DrizzleDriver
       - fineract_tenants_url=jdbc:mysql:thin://fineractmysql:3306/fineract_tenants
       - fineract_tenants_uid=root