Fix(eos_cli_config_gen): Fix the logic for action in event-handler

[Shivani-gslab]

          One more thing i noticed that when i do not give action for any trigger then playbook get error on documentation. 

TASK [arista.avd.eos_cli_config_gen : Generate device documentation] *********************************************************************
fatal: [leaf1-dc1 -> localhost]: FAILED! => {"msg": "'dict object' has no attribute 'action'. 'dict object' has no attribute 'action'"}

Originally posted by @MaheshGSLAB in https://github.com/aristanetworks/avd/pull/3878#pullrequestreview-2017297537

Need to fix the schema and logic for action_type and action in both documentation and config template. Checked in EOS >= 4.30