Update environment variable that is used for sql_alchemy_conn

[adwk67]

In airflow version 2.2.5 the value for sql_alchemy_conn is held in AIRFLOW__CORE__SQL_ALCHEMY_CONN - this is the variable currently used in the airflow operator.

In version 2.6.1 this is now AIRFLOW__DATABASE__SQL_ALCHEMY_CONN. This should be updated as deprecation warnings are being logged.