GentleSwallow91 notice this part:
Hi Martin. Sorry - missed your reply.
Yeap I am aware that docker_internal_mounts is inside agent section.
'-v', '/tmp/ssh-XXXXXXnfYTo5/agent.8946:/tmp/ssh-XXXXXXnfYTo5/agent.8946', '-e', 'SSH_AUTH_SOCK=/tmp/ssh-XXXXXXnfYTo5/agent.8946',

It is creating a copy of the ssh folder and setting the SSH_AUTH_SOCK env to it. You can just map the entire ssh folder automatically by un-setting SSH_AUTH_SOCK before running the agent.
SSH_AUTH_SOCK= clearml-agent ...