don't use $() in system tests

(cherry picked from commit bf9c6007)
14 jobs for 539-shell-style-fixes-v9_12 in 7 minutes and 18 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Precheck
passed #56583
amd64 docker linux
precheck:debian:sid:amd64

00:00:16

 
  Build
passed #56584
amd64 docker linux
build:centos:centos6:amd64

00:02:02

passed #56585
amd64 docker linux
build:centos:centos7:amd64

00:02:02

passed #56586
amd64 docker linux
build:debian:sid:amd64

00:01:28

passed #56587
i386 docker linux
build:debian:sid:i386

00:01:23

 
  Test
passed #56596
amd64 docker linux
install:debian:sid:amd64

00:02:07

passed #56592
amd64 docker linux
systemtest:centos:centos6:amd64

00:04:48

passed #56593
amd64 docker linux
systemtest:centos:centos7:amd64

00:04:40

passed #56594
amd64 docker linux
systemtest:debian:sid:amd64

00:04:41

passed #56595
i386 docker linux
systemtest:debian:sid:i386

00:04:57

passed #56588
amd64 docker linux
unittest:centos:centos6:amd64

00:01:04

passed #56589
amd64 docker linux
unittest:centos:centos7:amd64

00:00:46

passed #56590
amd64 docker linux
unittest:debian:sid:amd64

00:00:56

passed #56591
i386 docker linux
unittest:debian:sid:i386

00:00:59