Fix bad version check writing Repository nodes (#30846)

The writeTo method of VerifyRepositoryResponse incorrectly used its
local version to determine what it was receiving, rather than the
sender's version. This fixes a bug that ocassionally happened when a 6.4
master node sent data to a 7.0 client, causing the number of bytes to be
improperly read. This also unmutes the test.

Closes #30807

server/src/main/java/org/elasticsearch/action/admin/cluster/repositories/verify/VerifyRepositoryResponse.java

@@ -151,7 +151,7 @@ public void readFrom(StreamInput in) throws IOException {
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);
-        if (Version.CURRENT.onOrAfter(Version.V_6_4_0)) {
+        if (out.getVersion().onOrAfter(Version.V_6_4_0)) {
             out.writeList(getNodes());
         } else {
             clusterName.writeTo(out);