Reassign an agent
[Required authorization] Route required privileges: fleet-agents-all.
POST
/api/fleet/agents/{agentId}/reassign
curl \
--request POST 'http://localhost:5601/api/fleet/agents/{agentId}/reassign' \
--header "Authorization: $API_KEY" \
--header "Content-Type: application/json" \
--header "kbn-xsrf: true" \
--data '{"policy_id":"string"}'