Investigate failing Aggreg test in kube-conformance e2e.test

Even after bumping the k8s tests to 1.15.x baseline, which includes proper support for the etcd container image selection (previous versions hardcoded an x86 specific image), the Aggregation layer testcase still fails on IEC, for both x86_64 and aarch64 architectures.

This might be a configuration issue or an incompatible testing suite configuration, but we're still investigating the exact rootcause.