warn, rather than failing, if kyua is not present

(cherry picked from commit 6cfb2249)
19 jobs for 4-warn-not-fail-v9_11 in 8 minutes and 59 seconds (queued for 10 seconds)
Status Job ID Name Coverage
  Precheck
passed precheck:debian:sid:amd64 #97821
linux docker amd64

00:00:22

canceled precheck:debian:sid:amd64 #97772
amd64 docker linux

00:04:15

 
  Build
passed build:centos:centos6:amd64 #97773
amd64 docker linux

00:02:37

passed build:centos:centos7:amd64 #97774
amd64 docker linux

00:02:50

passed build:debian:sid:amd64 #97775
amd64 docker linux

00:01:43

passed build:debian:sid:i386 #97776
i386 docker linux

00:02:29

passed noassert:build:debian:sid:amd64 #97777
amd64 docker linux

00:01:25

 
  Test
skipped docs:debian:sid:amd64 #97778
amd64 docker linux
passed install:debian:sid:amd64 #97787
amd64 docker linux

00:03:35

passed noassert:systemtest:debian:sid:amd64 #97789
amd64 docker linux

00:05:00

passed noassert:unittest:debian:sid:amd64 #97788
amd64 docker linux

00:01:01

passed systemtest:centos:centos6:amd64 #97783
amd64 docker linux

00:04:46

passed systemtest:centos:centos7:amd64 #97784
amd64 docker linux

00:04:35

passed systemtest:debian:sid:amd64 #97785
amd64 docker linux

00:04:58

passed systemtest:debian:sid:i386 #97786
i386 docker linux

00:05:11

skipped unittest:centos:centos6:amd64 #97779
amd64 docker linux
skipped unittest:centos:centos7:amd64 #97780
amd64 docker linux
passed unittest:debian:sid:amd64 #97781
amd64 docker linux

00:01:00

passed unittest:debian:sid:i386 #97782
i386 docker linux

00:01:02