Running Talker Example Via Apt Install Attempts to Access Undefined Environment Variable

[KDharmarajanDev]

Describe the bug
When running the talker.aws.py example in fogros2_examples when fogros2_examples is apt installed, the code attempts to read the environment variable COLCON_PREFIX_PATH in cloud_instance.py in line 57, but since this is an apt-installed packaged, this environment variable is None.

To Reproduce
Steps to reproduce the behavior:

1. Install ROS 2 Humble on Ubuntu 22.04.
2. Apt install ros-humble-fogros2 and ros-humble-fogros2-examples.
3. Apt install further unlisted dependencies using the README.md
4. Try running the talker example