Improve Source Context Docs

### Description

As documented here https://github.com/getsentry/sentry-docs/issues/7134#issuecomment-2668909598 our docs on Source Context could use some improvement.

This applies especially to Java which has Maven that further complicates the already long page.
I'll still label this with "Platform: Android" as well and leave it to the Android team to evaluate whether this is relevant for them or not.

先查看連結的 sentry-docs issue 和留言，然後檢查現有的 Java SDK Source Context 文件及其 Maven 設定。將頁面目前的指引與回報的問題進行比較，評估 Android 是否需要相同的處理，並在相關指引更加清楚後視為工作完成。

由索引模型根據 Issue 內容生成。