feat(agentloadtesting): restructred loadtesting under perf command with backward compatibility (#552)

* feat(agentloadtesting): restructred loadtesting under perf command with backward compatibility

* fixed readme formatting to default

* updated readme

* restructred load test commands under perf command

Author: s-hamdananwar

README.md

@@ -370,7 +370,7 @@ The agent load testing utility allows you to dispatch a running agent to a numbe
 To start an agent load test:
 
 ```shell
-lk agent-load-test \
+lk perf agent-load-test \
   --rooms 5 \
   --agent-name test-agent \
   --echo-speech-delay 10s \

cmd/lk/agent_loadtest.go

@@ -69,8 +69,7 @@ func main() {
 	app.Commands = append(app.Commands, IngressCommands...)
 	app.Commands = append(app.Commands, SIPCommands...)
 	app.Commands = append(app.Commands, ReplayCommands...)
-	app.Commands = append(app.Commands, LoadTestCommands...)
-	app.Commands = append(app.Commands, AgentLoadTestCommands...)
+	app.Commands = append(app.Commands, PerfCommands...)
 
 	// Register cleanup hook for SIGINT, SIGTERM, SIGQUIT
 	ctx, stop := signal.NotifyContext(