kafka.py: increase max size packet able to be produced (1 MB -> 5 MB)

6 jobs for feature-kafka_client_producer_size in 4 minutes and 55 seconds (queued for 15 seconds)
Status Name Job ID Coverage
  Dist
passed dist:tarball #1533184

00:00:18

 
  Build
passed build:debian:buster #1533186

00:01:20

passed build:el7 #1533185

00:00:45

passed docs #1533187

00:02:36

 
  Test
passed test:debian:buster #1533189

00:00:29

31.0%
passed test:el7 #1533188

00:00:45

31.0%