update opentelemetry span attributes

Author: pjirsa

semantickernel-api/src/main/java/com/microsoft/semantickernel/implementation/telemetry/ChatCompletionSpan.java

@@ -104,8 +104,8 @@ public void endSpanWithUsage(ChatCompletions chatCompletions) {
         CompletionsUsage usage = chatCompletions.getUsage();
         getSpan().setStatus(StatusCode.OK);
         getSpan()
-            .setAttribute("gen_ai.response.completion_tokens", usage.getCompletionTokens());
-        getSpan().setAttribute("gen_ai.response.prompt_tokens", usage.getPromptTokens());
+            .setAttribute("gen_ai.usage.output_tokens", usage.getCompletionTokens());
+        getSpan().setAttribute("gen_ai.usage.input_tokens", usage.getPromptTokens());
         close();
     }