Remove --since-time Flag in IPFIX Collector Log Retrieval

In this commit we eliminate the `--since-time` flag utilized when retrieving logs from the IPFIX collector Pod in the e2e test. We also use labels to filter records in the IPFIX collector Pod and the ClickHouse instead of using timestamp to do that.

The reason is that there is a potential time discrepancy between the testbed and the Kubernetes nodes or the time discrepancy between the k8s nodes, and using this flag/timestamp might prevent us from obtaining the desired logs.

For flows requiring correlation, such as inter-node traffic, if the records aren't received from both nodes, the record will remain in the queue for up to 3 cycles of aggregatorActiveFlowRecordTimeout.
We've set the timeout to exporterActiveFlowExportTimeout plus aggregatorActiveFlowRecordTimeout multiplied by 3 to ensure stability in the interNode test and facilitate the timely observation of removal messages.

Signed-off-by: Yun-Tang Hsu <hsuy@vmware.com>

ci/kind/test-e2e-kind.sh

@@ -275,7 +275,7 @@ function run_test {
   fi
 
   if $flow_visibility; then
-      timeout="20m"
+      timeout="25m"
       flow_visibility_args="-run=TestFlowAggregator --flow-visibility"
       if $coverage; then
           $FLOWAGGREGATOR_YML_CMD --coverage | docker exec -i kind-control-plane dd of=/root/flow-aggregator-coverage.yml