Use @app_env_config instead of @env_config

Check pull request #9789 for more information.
Initialize @app_env_config now that the var name has changed

Check 862389c9537dbb6f65fd26c4325e07607ed437b5 for more background.
drop an unused hash; change slang to SPECIAL
Merge pull request #9792 from vipulnsward/drop_unused_hash

drop an unused hash; change slang to SPECIAL