fix: pass --insecure-registry to ko for plain-HTTP KinD registry

ko >=v0.19 writes SBOMs to the registry over HTTPS by default, which
fails against the plain-HTTP KinD registry (registry.local:5000) with:
"http: server gave HTTP response to HTTPS client"

Set KO_FLAGS=--insecure-registry in the e2e workflow and thread it
through ko resolve calls in e2e-common.sh.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: khrm

.github/workflows/e2e-matrix.yml

@@ -21,6 +21,9 @@ jobs:
       CLUSTER_DOMAIN: c${{ github.run_id }}.local
       ARTIFACTS: ${{ github.workspace }}/artifacts
       KOCACHE: /tmp/ko-cache
+      # registry.local:5000 is a plain-HTTP KinD registry; tell ko to skip TLS
+      # so that both image pushes and SBOM writes (ko >=v0.19) use plain HTTP.
+      KO_FLAGS: --insecure-registry
 
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0

test/e2e-common.sh

@@ -54,7 +54,7 @@ function install_triggers_crd() {
   echo ">> Deploying Tekton Triggers"
   rel=$(mktemp)
   release=$(mktemp)
-  ko resolve -f config/ > "${rel}" || fail_test "Tekton Triggers build failed"
+  ko resolve ${KO_FLAGS:-} -f config/ > "${rel}" || fail_test "Tekton Triggers build failed"
 
   if [ "${SKIP_SECURITY_CTX}" == "true" ]; then
       yq 'del(.spec.template.spec.containers[]?.securityContext.runAsUser, .spec.template.spec.containers[]?.securityContext.runAsGroup)' "${rel}" > "${release}"
@@ -66,7 +66,7 @@ function install_triggers_crd() {
 
   # Wait for the Interceptors CRD to be available before adding the core-interceptors
   kubectl wait --for=condition=Established --timeout=30s crds/clusterinterceptors.triggers.tekton.dev
-  ko resolve -f config/interceptors > "${rel}" || fail_test "Core interceptors build failed"
+  ko resolve ${KO_FLAGS:-} -f config/interceptors > "${rel}" || fail_test "Core interceptors build failed"
 
   if [ "${SKIP_SECURITY_CTX}" == "true" ]; then
       kubectl patch configmap config-defaults-triggers -n tekton-pipelines --type='merge' -p='{"data":{"default-run-as-user":"","default-fs-group":"", "default-run-as-group":""}}'