image: add hydrophone binary to the kubetest2 image

[ytsssun]

Issue #, if available:
N/A

Description of changes:
This PR adds the support to bundle hydrophone binary to the kubetest2 image. This allows the tester like exec or multi to use hydrophone to run the conformance test suites.

Test done:
Ran below command on an existing cluster

docker run --rm \
    --network host \
    -v ./test-eks-cluster.yaml:/config/test-eks-cluster.yaml \
    -it kubetest2 \
    kubetest2 eksctl \
    --cluster-name=x86-64-k8s1-34-cluster \
    --config-file=/config/test-eks-cluster.yaml \
    --region=us-west-2 \
    --deploy-target nodegroup \
    --nodegroup-name=ng-bottlerocket
    --up \
    --down --test=exec -- hydrophone --conformance --parallel 

And the tests passed:

Ran 424 of 7137 Specs in 2390.896 seconds
SUCCESS! -- 424 Passed | 0 Failed | 0 Pending | 6713 Skipped

Ginkgo ran 1 suite in 39m55.137761468s
Test Suite Passed
2026/01/24 00:10:09 Saving results at /tmp/results
00:10:11 INF Tests finished after 39m54s.
00:10:11 INF Downloading e2e.log to e2e.log...
00:10:11 INF Downloading junit_01.xml to junit_01.xml...
00:10:11 INF Waiting for Pod to terminate...
00:10:11 INF Container conformance-container terminated.
00:10:11 INF Deleted ClusterRoleBinding conformance-serviceaccount-role:conformance.
00:10:11 INF Deleted ClusterRole conformance-serviceaccount:conformance.
00:10:12 INF Waiting for Namespace conformance to be deleted.
00:10:54 INF Deleted Namespace conformance.
00:10:54 INF Tests completed successfully.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.