fix(lego_openbao): only restart containers if they exist

[sebastian-de]

While deploying a new host I discovered that this role fails if the containers defined in lego_openbao_restart_container_names don't exist, yet.

[cursor]

PR Summary

Low Risk
Small Ansible handler fix that only skips restarting missing containers; no auth, secrets, or core certificate logic changes.

Overview
Makes the restart_containers handler resilient on fresh hosts by checking container existence before restarting.

Previously it looped lego_openbao_restart_container_names directly and failed when named containers were missing. It now queries docker_container_info first and restarts only containers that already exist.

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[sebastian-de]

/fast-forward