Fix Dockerfile permissions

[yatharthranjan]

Currently, we copy our modified launcher in the Dockerfile

# Load modified launcher
COPY ./docker/launch /etc/confluent/docker/launch

But in the latest confluent base images the default user is appuser and not root, so we need to change the permissions of the copied files so they can be access by the appuser.

Here is the difference in permissions - In our image -rwxrwxr-x 1 root root 2440 Jun 1 14:32 /etc/confluent/docker/launch In confluent base image -rwxr-xr-x 1 appuser appuser 2.1K Aug 13 2021 /etc/confluent/docker/launch

This probably happened when we upgraded to 6.2.x as in 5.2.x the default user is root in base image.

[yatharthranjan]

Closed by #94