Issue #SB-26347 fix: change the nodebb database from mongo to redis (#2835)

* Issue #SB-26347 fix: change the nodebb database from mongo to redis

ansible/roles/stack-sunbird/templates/sunbird_nodebb.env

 # Initialization variable for mongo
 # Ref: https://community.nodebb.org/topic/4325/set-up-nodebb-via-environment-variables
-database=mongo
+database=redis
+# redis database number
+redis_database={{nodebb_redis_database|default(4)}}
+# declearing js heap memory size
+NODE_OPTIONS={{nodebb_heap_size|default(1024)}}
 secret={{nodebb_hash_key|default('1d57ba64-86d4-43ff-bd10-f6e9e0782899')}}
 url=http://0.0.0.0:4567/discussions/
-mongo__host={{mongo_nodebb_host}}
-mongo__database=nodebb
+redis__host={{sunbird_lp_redis_host }}
+redis__port=6379
+redis__username={{nodebb_redis_username|default('')}}
+redis__password={{nodebb_redis_password|default('')}}
+redis__database=redis_database
 # password won't get overwritten if you run
 # 'node app --setup' multiple times
 # Default username is admin