ci: fix LU verification to check array length instead of path

The SCSILu.Path field is not populated during LU creation, so grep
for the file path won't work. Use python3 JSON validation to check
the array length instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/gotgt.yml

@@ -207,7 +207,7 @@ jobs:
         echo "--- verify new lu in list ---"
         curl -sf "$API/lu/list?target=$NEW_TARGET" | tee /tmp/list_lu2.out
         echo ""
-        grep -q "ci_disk.img" /tmp/list_lu2.out
+        python3 -c "import json,sys; data=json.load(sys.stdin); assert len(data)==1, f'expected 1 LU, got {len(data)}'" < /tmp/list_lu2.out
         echo "PASS: new LU visible in list"
 
         # 8. Remove the LU
@@ -224,10 +224,7 @@ jobs:
         echo "--- verify lu removed ---"
         curl -sf "$API/lu/list?target=$NEW_TARGET" | tee /tmp/list_lu3.out
         echo ""
-        if grep -q "ci_disk.img" /tmp/list_lu3.out; then
-          echo "FAIL: LU still present after removal"
-          exit 1
-        fi
+        python3 -c "import json,sys; data=json.load(sys.stdin); assert len(data)==0, f'expected 0 LUs, got {len(data)}'" < /tmp/list_lu3.out
         echo "PASS: LU no longer in list"
 
         # 10. Remove the target