Change execution order of the legacy async batch read operation in k6 suite

- run the test after the parallel cases
- add 30 seconds safe-period of time waiting for completion of
  active threads (remained from previous test cases)

Issue-ID: CPS-2414

Change-Id: I1260b37cd4f1974eebcccf867b36172b407a9646
Signed-off-by: halil.cakal <halil.cakal@est.tech>
diff --git a/k6-tests/ncmp/ncmp-kpi.js b/k6-tests/ncmp/ncmp-kpi.js
index 05500a6..f9a19c3 100644
--- a/k6-tests/ncmp/ncmp-kpi.js
+++ b/k6-tests/ncmp/ncmp-kpi.js
@@ -47,6 +47,7 @@
 });
 
 const DURATION = '15m';
+const LEGACY_BATCH_THROUGHPUT_TEST_START_TIME = '15m30s';
 
 export const options = {
     setupTimeout: '8m',
@@ -93,14 +94,14 @@
             exec: 'legacyBatchProduceScenario',
             vus: 2,
             iterations: LEGACY_BATCH_THROUGHPUT_TEST_NUMBER_OF_REQUESTS,
-            maxDuration: DURATION,
+            startTime: LEGACY_BATCH_THROUGHPUT_TEST_START_TIME,
         },
         legacy_batch_consume_scenario: {
             executor: 'per-vu-iterations',
             exec: 'legacyBatchConsumeScenario',
             vus: 1,
             iterations: 1,
-            maxDuration: DURATION,
+            startTime: LEGACY_BATCH_THROUGHPUT_TEST_START_TIME,
         }
     },
     thresholds: {