Force use of Net::DNS 1.15 in CentOS images

Net::DNS 1.16 introduced a DNS compression bug which breaks BIND system
tests.  Prevent CI errors by temporarily forcing use of Net::DNS 1.15
in CentOS Docker images.
20 jobs for force-install-perl-modules-from-cpan in 9 minutes and 39 seconds (queued for 17 seconds)
Status Job ID Name Coverage
  Images
passed #25390
amd64 docker linux manual
centos_centos6_amd64

00:09:39

passed #25391
amd64 docker linux manual
centos_centos7_amd64

00:07:12

manual #25394
amd64 docker linux allowed to fail manual
debian_buster_amd64
manual #25403
i386 docker linux allowed to fail manual
debian_buster_i386
manual #25405
amd64 docker linux allowed to fail manual
debian_experimental_amd64
manual #25392
amd64 docker linux allowed to fail manual
debian_jessie_amd64
manual #25401
i386 docker linux allowed to fail manual
debian_jessie_i386
manual #25395
amd64 docker linux allowed to fail manual
debian_sid_amd64
manual #25396
arm64 docker linux allowed to fail manual
debian_sid_arm64
manual #25404
allowed to fail manual
debian_sid_i386
manual #25393
amd64 docker linux allowed to fail manual
debian_stretch_amd64
manual #25402
i386 docker linux allowed to fail manual
debian_stretch_i386
manual #25399
amd64 docker linux allowed to fail manual
ubuntu_artful_amd64
manual #25408
i386 docker linux allowed to fail manual
ubuntu_artful_i386
manual #25400
amd64 docker linux allowed to fail manual
ubuntu_bionic_amd64
manual #25409
i386 docker linux allowed to fail manual
ubuntu_bionic_i386
manual #25397
amd64 docker linux allowed to fail manual
ubuntu_trusty_amd64
manual #25406
i386 docker linux allowed to fail manual
ubuntu_trusty_i386
manual #25398
amd64 docker linux allowed to fail manual
ubuntu_xenial_amd64
manual #25407
i386 docker linux allowed to fail manual
ubuntu_xenial_i386