## What changes were proposed in this pull request?
The current test is incorrect, because
- The expected number of messages does not take into account that the topic has 2 partitions, and rate is set per partition.
- Also in some cases, the test ran out of data in Kafka while waiting for the right amount of data per batch.
The PR
- Reduces the number of partitions to 1
- Adds more data to Kafka
- Runs with 0.5 second so that batches are created slowly
## How was this patch tested?
Ran many times locally, going to run it many times in Jenkins
(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)
Author: Tathagata Das <tathagata.das1565@gmail.com>
Closes#14361 from tdas/kafka-rate-test-fix.
03c27435ae