Remove octetDeltaCount check in flow-visibility e2e test

In this commit, we do:

1. Adjust the flow-visibility end-to-end test by disabling the octetDeltaCount check. This modification is necessary because, when the dual-stack cluster is enabled, the time taken to retrieve logs from the IPFIX collector Pod is significantly longer (around 4 seconds). In the e2e test, we regularly checked the logs every 500 milliseconds to ensure that we didn't receive the last record (where octetDeltaCount is 0). However, due to the delay, the PollImmediately() function doesn't execute every 500 milliseconds. Therefore, we have removed the octetDeltaCount check and, instead, filter out all records with octetDeltaCount=0 when retrieving records from the IPFIX collector Pod.

2. Confirm the correct addition of a label to a specific Pod after updating the Pod.

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