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

(cherry picked from commit 8f15219f)
18 jobs for cmocka-silence-v9_12 in 9 minutes and 32 seconds (queued for 8 seconds)
Status Job ID Name Coverage
  Precheck
passed precheck:debian:sid:amd64 #97891
amd64 docker linux

00:00:22

 
  Build
passed build:centos:centos6:amd64 #97892
amd64 docker linux

00:03:15

passed build:centos:centos7:amd64 #97893
amd64 docker linux

00:03:30

passed build:debian:sid:amd64 #97894
amd64 docker linux

00:03:19

passed build:debian:sid:i386 #97895
i386 docker linux

00:02:17

passed noassert:build:debian:sid:amd64 #97896
amd64 docker linux

00:02:22

 
  Test
passed docs:debian:sid:amd64 #97897
amd64 docker linux

00:00:47

passed install:debian:sid:amd64 #97906
amd64 docker linux

00:03:19

passed noassert:systemtest:debian:sid:amd64 #97908
amd64 docker linux

00:04:48

passed noassert:unittest:debian:sid:amd64 #97907
amd64 docker linux

00:00:53

passed systemtest:centos:centos6:amd64 #97902
amd64 docker linux

00:04:55

passed systemtest:centos:centos7:amd64 #97903
amd64 docker linux

00:04:52

passed systemtest:debian:sid:amd64 #97904
amd64 docker linux

00:04:55

passed systemtest:debian:sid:i386 #97905
i386 docker linux

00:05:07

passed unittest:centos:centos6:amd64 #97898
amd64 docker linux

00:00:46

passed unittest:centos:centos7:amd64 #97899
amd64 docker linux

00:00:48

passed unittest:debian:sid:amd64 #97900
amd64 docker linux

00:00:46

passed unittest:debian:sid:i386 #97901
i386 docker linux

00:00:45