ci(e2e): fix ko >=v0.19 SBOM push failure on plain-HTTP registry

ko v0.19 unconditionally attempts HTTPS when writing SBOMs, causing
the E2E job to fail with "http: server gave HTTP response to HTTPS
client" against the plain-HTTP KinD registry (registry.local:5000).

Set KO_FLAGS=--insecure-registry in the e2e-matrix env block so that
both image pushes and SBOM writes use plain HTTP for the local
registry. The flag is already forwarded to `ko apply` via $(KO_FLAGS)
in the Makefile apply target, so no Makefile change is needed.

Signed-off-by: Jawed khelil <jkhelil@redhat.com>
Assisted-by: Claude Sonnet 4.6 (via Cursor)
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: 2 people

.github/workflows/e2e-matrix.yml

@@ -29,6 +29,9 @@ jobs:
           k8s-version: v1.34.x
     env:
       KO_DOCKER_REPO: registry.local:5000/tekton
+      # 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
       CLUSTER_DOMAIN: c${{ github.run_id }}.local
       ARTIFACTS: ${{ github.workspace }}/artifacts