Promote agnhost 2.51

Author: riendeau

registry.k8s.io/images/k8s-staging-e2e-test-images/images.yaml

@@ -27,6 +27,7 @@
     "sha256:cc249acbd34692826b2b335335615e060fdb3c0bca4954507aa3a1d1194de253": ["2.47"]
     "sha256:baeac1023bb8b281cffcd4246217331a9977c7cb8e285c0d6f07228855df49f6": ["2.48"]
     "sha256:0737a4bf9ddaef39caf5ab80ba87d5581c13db9fe11ad96fb10a5a85c687d570": ["2.50"]
+    "sha256:488b351e3b19126c378adadd4a2405519dd3ee2533bf172e7c7be0642660ce78": ["2.51"]
 - name: apparmor-loader
   dmap:
     "sha256:60629fe42de6260c9b930b48a2923b69168dc1c71fa5f762f70036477ffd74b6": ["1.2"]