Fixes:
Updated config parameter name to agent-isolation-mode
Updated all code variables from secure_agent_users to agent_isolation_mode
Updated all documents to use agent isolation mode instead of secure mode.
Updated volttron-upgrade command to look for "secure-agent-users" parameter in volttron config and replace it with "agent-isolation-mode" if param exists
Tested by run pytests, setup script and upgrade script. Build rst docs locally to verify links to renamed documents
Fixes issue #3035
Fixes: Updated config parameter name to agent-isolation-mode Updated all code variables from secure_agent_users to agent_isolation_mode Updated all documents to use agent isolation mode instead of secure mode. Updated volttron-upgrade command to look for "secure-agent-users" parameter in volttron config and replace it with "agent-isolation-mode" if param exists Tested by run pytests, setup script and upgrade script. Build rst docs locally to verify links to renamed documents