fix(ci): detect riscv64 system test failures by checking output

The riscv64 system test step only checked the cmake exit code, which
is always 0 even when individual tests fail inside QEMU. Align with
the aarch64 approach: capture output to file, grep for "Failed: 0"
to determine pass/fail.

Signed-off-by: Niu Zhihong <zhihong@nzhnb.com>

Author: MRNIU

.github/workflows/workflow.yml

@@ -53,7 +53,9 @@ jobs:
         run: |
           for i in $(seq 1 $SYSTEM_TEST_RUNS); do
             echo "=== riscv64 System Test Run $i/$SYSTEM_TEST_RUNS ==="
-            if ! timeout 300 cmake --build build_riscv64 --target system_test_run; then
+            timeout 300 cmake --build build_riscv64 --target system_test_run > /tmp/st_out_$i.txt 2>&1 || true
+            cat /tmp/st_out_$i.txt
+            if ! grep -q "Failed: 0" /tmp/st_out_$i.txt; then
               echo "riscv64 system test run $i/$SYSTEM_TEST_RUNS FAILED"
               exit 1
             fi