[TRTLLM-9579][infra] Set mergeWaiveList stage UNSTABLE when there is any issue (#9692)

Signed-off-by: Yiqing Yan <yiqingy@nvidia.com>

jenkins/L0_MergeRequest.groovy

@@ -371,8 +371,11 @@ def mergeWaiveList(pipeline, globalVars)
     } catch (InterruptedException e) {
         throw e
     } catch (Exception e) {
-        echo "Merge test waive list failed. Error: ${e.toString()}"
-        echo "Fallback to use the default test waive list from the PR"
+        catchError(
+            buildResult: 'SUCCESS',
+            stageResult: 'UNSTABLE') {
+            error "Merge test waive list failed. Fallback to use the default test waive list from the PR. Error: ${e.toString()}"
+        }
     }
 }
 

jenkins/L0_Test.groovy

@@ -2207,6 +2207,8 @@ ${reusedTestsContent}
 REUSED_TESTS_EOF
 """)
             echo "Appended ${reusedTests.size()} reused tests to ${waivesTxt}"
+        } else {
+            echo "No reused tests found"
         }
     } catch (InterruptedException e) {
         throw e