CASSANDRA-20181: Remove obsolete cqlsh Dockerfiles on 4.1

pylib/README.asc

@@ -5,7 +5,6 @@ This directory contains code primarily for cqlsh. cqlsh uses cqlshlib in this di
 == Requirements
 . Python 3.6+ (for cqlsh)
 . virtualenv
-. Docker (optional)
 
 == Running tests
 
@@ -22,23 +21,3 @@ You can run tests with a local Cassandra server simply by -
 
 In order to run tests in a virtual environment for cqlshlib, run cassandra-cqlsh-tests.sh in this directory. It will
 automatically setup a virtualenv with the appropriate version of Python and run tests inside it.
-
-There are Dockerfiles that can be used to test whether cqlsh works with a default, barebones
-Python installation. Assuming Cassandra's source is checked out at `$CASSANDRA_DIR`. To test, first
-build the Docker image containing the barebones Python installation -
-
-  $ docker build . --file Dockerfile.ubuntu.py3 -t ubuntu-lts-py3
-
-Next, run cqlsh inside the newly built image -
-
-  $ docker run -v $CASSANDRA_DIR:/code -it ubuntu-lts-py3:latest /code/bin/cqlsh host.docker.internal
-
-If `host.docker.internal` isn't supported, then you can use `--net="host"` with `docker run`:
-
-  $ docker run --net="host" -v $CASSANDRA_DIR:/code -it ubuntu-lts-py3:latest /code/bin/cqlsh
-
-This will try to spawn a cqlsh instance inside the Docker container running Ubuntu LTS (18.04)
-with minimal Python installation. It will try to connect to the Cassandra instance running on the
-Docker host at port 9042. If you have Cassandra running elsewhere, replace host.docker.internal
-with the IP / hostname as usual. Please ensure that the IP / host is accessible from _within_ the
-Docker container.