Detect async servlet mode and noop

### Problem Statement

The SDK is leaking memory (through scopes) if servlets are used in async mode.

### Solution Brainstorm

Detect that servlets are used in async mode and noop in SentryServletRequestListener.
Possibly suggest using our OTel integration: https://docs.sentry.io/platforms/java/guides/servlet/opentelemetry/

從 SentryServletRequestListener 開始，查看連結的 OpenTelemetry servlet 整合指南。確定如何偵測非同步 servlet 模式，以及應在哪裡讓請求處理變成 no-op；當使用非同步 servlet 不再洩漏 scopes，且相關測試涵蓋此行為時，即表示完成。

由索引模型根據 Issue 內容生成。