METRON-2227 - Increase Kafka test harness timeout

[tigerquoll]

On slower machines the Kafka test harness can timeout on a hardcoded 5 second timeout buried deep in the Kafka test harness code. This patch factors the timeout into a constant and doubles it to 10 seconds, which makes the test pass a lot more reliably on my build host.

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[mmiklavc]

I was on the fence about whether this should just be a string or not, but I think having the numeric constants consistently numeric like this makes it a bit cleaner.

[mmiklavc]

Thanks for the contribution. Only 1 minor change regarding the commented out test. Get that resolved and we're good to go. +1 by inspection.

[mmiklavc]

+1