cmd/k8s-operator/e2e: support real clusters and registries (#20911)

Extend e2e test setup to work with a remote registry and real cluster.
Previously only kind was supported.

Detect cluster node architecture and build images only for the given
architecture to reduce build time. Build for all platforms as the fallback
option. This assumes only one node architecture per cluster, which is
reasonable for our test cases.

By default, --build loads the built images into a kind cluster. Use with
--registry to instead specify and push to a remote registry.

Fixes tailscale/corp#46577

Signed-off-by: Becky Pauley <becky@tailscale.com>