Update container registry for docker

Update location of docker registry container to
gcr.io/kunit-prow-container-registry/kunit:latest since the old
container registry got deleted.

Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Change-Id: I0ffa24fa248844e15262dbf59708cacddcb50485
diff --git a/BUILD.bazel b/BUILD.bazel
index 577439c..199bb7c 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -38,7 +38,7 @@
     format = "Docker",
     image = ":kunit",
     registry = "gcr.io",
-    repository = "kunit-presubmit/kunit",
+    repository = "kunit-prow-container-registry/kunit",
     tag = "latest",
 )