remove (or hide behind a 'verbose' flag) extra output from system tests

(cherry picked from commit 8f15219f)
18 jobs for cmocka-silence-v9_11 in 7 minutes and 54 seconds (queued for 3 minutes and 14 seconds)
Status Job ID Name Coverage
  Precheck
passed precheck:debian:sid:amd64 #97909
linux amd64 docker

00:00:24

 
  Build
passed build:centos:centos6:amd64 #97910
amd64 docker linux

00:02:58

passed build:centos:centos7:amd64 #97911
amd64 docker linux

00:02:39

passed build:debian:sid:amd64 #97912
amd64 docker linux

00:01:56

passed build:debian:sid:i386 #97913
i386 docker linux

00:01:55

passed noassert:build:debian:sid:amd64 #97914
amd64 docker linux

00:02:21

 
  Test
passed docs:debian:sid:amd64 #97915
amd64 docker linux

00:00:50

passed install:debian:sid:amd64 #97924
amd64 docker linux

00:02:41

passed noassert:systemtest:debian:sid:amd64 #97926
amd64 docker linux

00:04:19

passed noassert:unittest:debian:sid:amd64 #97925
amd64 docker linux

00:01:01

passed systemtest:centos:centos6:amd64 #97920
amd64 docker linux

00:04:14

passed systemtest:centos:centos7:amd64 #97921
amd64 docker linux

00:04:18

passed systemtest:debian:sid:amd64 #97922
amd64 docker linux

00:04:16

passed systemtest:debian:sid:i386 #97923
i386 docker linux

00:04:31

passed unittest:centos:centos6:amd64 #97916
amd64 docker linux

00:01:00

passed unittest:centos:centos7:amd64 #97917
amd64 docker linux

00:01:02

passed unittest:debian:sid:amd64 #97918
amd64 docker linux

00:01:03

passed unittest:debian:sid:i386 #97919
i386 docker linux

00:00:58