Set up multiple Airflow instances under the same domain with different sessions

<!-- Welcome to Apache Airflow! Please complete the next sections or the issue will be closed. --> **Apache Airflow version**: v2.1.1 <!-- AIRFLOW VERSION IS MANDATORY --> **OS**: Ubuntu 20.04.2 LTS <!-- MANDATORY! You can get it via `cat /etc/oss-release` for example --> **Apache Airflow Provider versions**: Not relevent <!-- You can use `pip freeze | grep apache-airflow-providers` (you can leave only relevant ones)--> **Deployment**: AWS EC2 Instances <!-- e.g. Virtualenv / VM / Docker-compose / K8S / Helm Chart / Managed Airflow Service --> <!-- Please include your deployment tools and versions: docker-compose, k8s, helm, etc --> **What happened**: When using multiple Airflow instances (i.e. Production instance and a Development instance) the webserver navigation/redirection can send you back to the incorrect instance. <!-- Please include exact error messages if you can --> **What you expected to happen**: I expect when I press "Back" or "Save" within Airflow (for instance, when editing a 'pool' from the GUI' that it goes back to the previous page (of the instance I am working on, not a different instance that I happen to also be working with at the same time). <!-- What do you think went wrong? --> **How to reproduce it**: It seems both webserver instances are using the same cookie or session information. I am using a single NGINX reverse proxy to access both a dev instance and a prod instance (but with a unique URL to differentiate the two).. Example URLs: https://ec2-myIP.eu-central-1.compute.amazonaws.com/airflow [ points to the PRODUCTION instance ] https://ec2-myIP.eu-central-1.compute.amazonaws.com/airflow_dev [ points to the DEVELOPMENT instance ] Example ISSUE (using pools as an example, but it is not limited there): 1. On PRODUCTION instance browse to Admin->Pools 2. On DEVELOPMENT instance browse to Admin->Pools 3. On PRODUCTION instance click Airflows Back navigation arrow/button 4. On DEVELOPMENT instance browse to Admin->Pools, edit a pool,…