set fineract_tenants_* more nicely in docker-compose.yml

We can use environment variables instead of system properties.

We originally had to use system properties and could not use environment
variables, because these used to read by Tomcat, but since the switch
to Hikari in FINERACT-796 these are read by Spring Boot instead of
Tomcat, so we can now use system properties.

This both "looks nicer" and is useful e.g. for FINERACT-881.

docker-compose.yml

@@ -43,7 +43,11 @@ services:
     depends_on:
       - fineractmysql
     environment:
-      - JAVA_OPTS=-Dfineract_tenants_url=jdbc:mysql:thin://fineractmysql:3306/fineract_tenants -Dfineract_tenants_driver=org.drizzle.jdbc.DrizzleDriver -Dfineract_tenants_uid=root -Dfineract_tenants_pwd=skdcnwauicn2ucnaecasdsajdnizucawencascdca -Djava.awt.headless=true -XX:+UseG1GC -Dfile.encoding=UTF-8
+      - JAVA_OPTS=-Djava.awt.headless=true -XX:+UseG1GC -Dfile.encoding=UTF-8
+      - fineract_tenants_driver=org.drizzle.jdbc.DrizzleDriver
+      - fineract_tenants_url=jdbc:mysql:thin://fineractmysql:3306/fineract_tenants
+      - fineract_tenants_uid=root
+      - fineract_tenants_pwd=skdcnwauicn2ucnaecasdsajdnizucawencascdca 
       - FINERACT_DEFAULT_TENANTDB_HOSTNAME=fineractmysql
       - FINERACT_DEFAULT_TENANTDB_PORT=3306
       - FINERACT_DEFAULT_TENANTDB_UID=root