[Keystore]Fix abort unsafe check in keystore fuzz

Fuzzer finds issue when checking return message after response code
fails.

```
m -j$(nproc) keystore2_unsafe_fuzzer
adb sync data
adb shell /data/fuzz/${TARGET_ARCH}/keystore2_unsafe_fuzzer/keystore2_unsafe_fuzzer
```

Test: description
Bug: 292231203
Change-Id: I27bdcb91fa05a75239aeeb34d817e4f04387b41f
1 file changed