feat(agent): reset default response format string #51

Modify the `responseFormat` property of `CustomAgentExecutor` to be an empty string. This change allows the `execute` function to work correctly with the updated response format.

src/main/kotlin/cc/unitmesh/devti/counit/CustomAgentExecutor.kt

@@ -21,7 +21,7 @@ class CustomAgentExecutor(val project: Project) : CustomSSEProcessor() {
     private val logger = logger<CustomAgentExecutor>()
 
     override var requestFormat: String = "{ \"messageKeys\": {\"role\": \"role\", \"content\": \"content\"} }"
-    override var responseFormat: String = "\$.choices[0].delta.content"
+    override var responseFormat: String = ""
 
     fun execute(input: String, agent: CustomAgentConfig): Flow<String>? {
         this.requestFormat = agent.connector?.requestFormat ?: this.requestFormat