[Test]github action测试fastdebug未真正运行

当前github action包含release、fastdebug两个类型build type的测试。但是实际上使用fastdebug build + 当前已有的Problemlist有多个失败用例，github action未能抓到相关用例报错。

虽然 CI 构建了 fastdebug 和 release 两个版本，但 test-cvm8+17.yml 第 95 行传入的 debug-level 参数硬编码为 release（而非使用矩阵参数）。因此测试步骤始终下载的是 release JDK 包，始终使用 MODE=release 运行 jtreg。

```yaml
- name: 'Get bundles'
with:
# 始终下载 release 包！
name: CompoundVM_${{ version }}_${{ platform }}_${{ inputs.debug-level }}.tar.gz

- name: 'Run tests'
run: |
# MODE 始终是 release！
make -f cvm.mk test_jtreg8_${{ matrix.test-suite }} SKIP_BUILD=true MODE=${{ inputs.debug-level }}
```

Start with .github/workflows/test-cvm8+17.yml, especially the bundle-download step around line 95 and the jtreg run step. Trace how the matrix debug-level value is passed into both steps, then run the workflow or its relevant test commands for release and fastdebug. Done means fastdebug tests use the fastdebug bundle and MODE, and failures from its existing ProblemList are reported by CI.

Written by the indexing model from the issue text.