fix(disconnected): set BUILDAH_ISOLATION=chroot for operator handler

The CI pod runs with nested_podman: true (hostUsers: false), placing
it inside a Linux user namespace. When prepare-restricted-environment.sh
calls podman build, podman tries to create another user namespace
inside the existing one, which fails with:

  newuidmap: open of uid_map failed: Permission denied
  Error: cannot set up namespace using /usr/bin/newuidmap: exit status 1

Export BUILDAH_ISOLATION=chroot before invoking the script so all
podman build / buildah calls use chroot isolation instead of nested
user namespaces. The env var is respected by both podman and buildah
without needing to modify the downstream rhdh-operator script.

Assisted-by: OpenCode

Author: zdrapela

.ci/pipelines/jobs/ocp-disconnected-operator.sh

@@ -51,6 +51,12 @@ handle_ocp_disconnected_operator() {
     )
   fi
 
+  # The CI pod runs with nested_podman: true (hostUsers: false), placing it
+  # inside a Linux user namespace. podman build tries to create another user
+  # namespace, which fails with "newuidmap: open of uid_map failed: Permission
+  # denied". BUILDAH_ISOLATION=chroot uses chroot instead of nested namespaces.
+  export BUILDAH_ISOLATION=chroot
+
   bash "${DISCONNECTED_TMPDIR}/prepare-restricted-environment.sh" "${prepare_args[@]}" \
     || {
       log::error "prepare-restricted-environment.sh failed — aborting"