BenTheElder: Shellcheck fixes

JobBuild
2849
11-08 06:48
pull-kind-build 1589872486093164544
pull-kind-conformance-parallel-ga-only 1589872486260936704
pull-kind-conformance-parallel-ipv6 1589872486294491136
pull-kind-e2e-kubernetes 1589872486218993664
pull-kind-e2e-kubernetes-1-20 1589872486948802560
pull-kind-e2e-kubernetes-1-21 1589872486437097472
pull-kind-e2e-kubernetes-1-22 1589872486411931648
pull-kind-e2e-kubernetes-1-23 1589872486361600000
pull-kind-e2e-kubernetes-1-24 1589872486328045568
pull-kind-test 1589872486135107584
pull-kind-verify 1589872486156079104