[BUG] Whole test body wrapped in catch (Throwable) {} (always green)

## Description
Both LRU/TinyLFU eviction tests put the entire logic + all `assertEquals` inside a try whose catch is `// just ignore`. Any `AssertionError`/NPE/logic bug is silently discarded -> test is green no matter what. Comment admits "results … not stable, just ignore".

## Location
```
shenyu-common/src/test/java/org/apache/shenyu/common/cache/MemorySafeLRUMapTest.java:40-65
shenyu-common/src/test/java/org/apache/shenyu/common/cache/MemorySafeWindowTinyLFUMapTest.java:73-76
```

## Impact
Core cache eviction correctness is effectively unverified.

## Suggested fix
Remove the try/catch; if memory-stability genuinely matters, isolate that one assertion behind `@Disabled` or `Assumptions.assumeTrue`, not a blanket swallow.

## Related existing issue(s)
None

_Identified during the 2026-08-02 audit; full list in [`docs/issue-candidates-2026-08-02.md`](docs/issue-candidates-2026-08-02.md)._

Start with shenyu-common/src/test/java/org/apache/shenyu/common/cache/MemorySafeLRUMapTest.java lines 40-65 and MemorySafeWindowTinyLFUMapTest.java lines 73-76. Run the two cache eviction tests, then inspect the try/catch around the assertions and preserve only any specifically justified memory-stability assumption. Done means assertion failures and unexpected errors make the tests fail rather than being swallowed.

Written by the indexing model from the issue text.