Reenable bwc tests after backport (#65954)

reenable bwc tests after backport

build.gradle

@@ -175,8 +175,8 @@ tasks.register("verifyVersions") {
  * after the backport of the backcompat code is complete.
  */
 
-boolean bwc_tests_enabled = false
-final String bwc_tests_disabled_issue = "https://github.com/elastic/elasticsearch/pull/65927" /* place a PR link here when committing bwc changes */
+boolean bwc_tests_enabled = true
+final String bwc_tests_disabled_issue = "" /* place a PR link here when committing bwc changes */
 if (bwc_tests_enabled == false) {
   if (bwc_tests_disabled_issue.isEmpty()) {
     throw new GradleException("bwc_tests_disabled_issue must be set when bwc_tests_enabled == false")

server/src/main/java/org/elasticsearch/search/internal/ShardSearchRequest.java

@@ -179,7 +179,7 @@ public class ShardSearchRequest extends TransportRequest implements IndicesReque
         super(in);
         shardId = new ShardId(in);
         searchType = SearchType.fromId(in.readByte());
-        shardIndex = in.getVersion().onOrAfter(Version.V_8_0_0) ? in.readVInt() : -1;
+        shardIndex = in.getVersion().onOrAfter(Version.V_7_11_0) ? in.readVInt() : -1;
         numberOfShards = in.readVInt();
         scroll = in.readOptionalWriteable(Scroll::new);
         source = in.readOptionalWriteable(SearchSourceBuilder::new);
@@ -247,7 +247,7 @@ public class ShardSearchRequest extends TransportRequest implements IndicesReque
         shardId.writeTo(out);
         out.writeByte(searchType.id());
         if (asKey == false) {
-            if (out.getVersion().onOrAfter(Version.V_8_0_0)) {
+            if (out.getVersion().onOrAfter(Version.V_7_11_0)) {
                 out.writeVInt(shardIndex);
             }
             out.writeVInt(numberOfShards);