Prepare to backport elastic#53793 (elastic#54010)

Update version in wire protocol and disable BWC.

build.gradle

@@ -222,8 +222,8 @@ task verifyVersions {
  * after the backport of the backcompat code is complete.
  */
 
-boolean bwc_tests_enabled = true
-final String bwc_tests_disabled_issue = "" /* place a PR link here when committing bwc changes */
+boolean bwc_tests_enabled = false
+final String bwc_tests_disabled_issue = "https://github.com/elastic/elasticsearch/pull/53793" /* 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/query/QuerySearchResult.java

@@ -320,7 +320,7 @@ public void readFromWithId(SearchContextId id, StreamInput in) throws IOExceptio
             }
         }
         setTopDocs(readTopDocs(in));
-        if (in.getVersion().before(Version.V_8_0_0)) {
+        if (in.getVersion().before(Version.V_7_7_0)) {
             InternalAggregations readAggs = null;
             if (hasAggs = in.readBoolean()) {
                 readAggs = new InternalAggregations(in);
@@ -398,7 +398,7 @@ public void writeToNoId(StreamOutput out) throws IOException {
             }
         } else {
             out.writeBoolean(true);
-            if (out.getVersion().before(Version.V_8_0_0)) {
+            if (out.getVersion().before(Version.V_7_7_0)) {
                 InternalAggregations aggs = aggregations.get();
                 aggs.writeTo(out);
                 if (out.getVersion().before(Version.V_7_2_0)) {