See here - specifically CLEARML_AGENT_SKIP_PYTHON_ENV_INSTALL
You'll need to make sure this env var is set before execution starts (you can set that in the custom bash script for the autoscaler instances).
This is actually not a very common scenario since the agent is designed to recreate the environment on the fly, building a docker image containing everything is not required, takes time and should be done again every time you need to change something, so we recommend just specifying your requirements and letting the agent do the work 🙂