adjust versions after backporting elastic#77691 (elastic#77784)

build.gradle

@@ -140,9 +140,9 @@ tasks.register("verifyVersions") {
  * after the backport of the backcompat code is complete.
  */
 
-boolean bwc_tests_enabled = false
+boolean bwc_tests_enabled = true
 // place a PR link here when committing bwc changes:
-String bwc_tests_disabled_issue = "https://github.com/elastic/elasticsearch/pull/76740"
+String bwc_tests_disabled_issue = ""
 /*
  * FIPS 140-2 behavior was fixed in 7.11.0. Before that there is no way to run elasticsearch in a
  * JVM that is properly configured to be in fips mode with BCFIPS. For now we need to disable

server/src/main/java/org/elasticsearch/search/aggregations/bucket/composite/InternalComposite.java

@@ -78,8 +78,7 @@ public InternalComposite(StreamInput in) throws IOException {
             formats.add(in.readNamedWriteable(DocValueFormat.class));
         }
         this.reverseMuls = in.readIntArray();
-        // TODO: use V_7_16_0 once PR is backported to 7.x
-        if (in.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (in.getVersion().onOrAfter(Version.V_7_16_0)) {
             this.missingOrders = in.readArray(MissingOrder::readFromStream, MissingOrder[]::new);
         } else {
             this.missingOrders = new MissingOrder[reverseMuls.length];
@@ -98,8 +97,7 @@ protected void doWriteTo(StreamOutput out) throws IOException {
             out.writeNamedWriteable(format);
         }
         out.writeIntArray(reverseMuls);
-        // TODO: use V_7_16_0 once PR is backported to 7.x
-        if (out.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (out.getVersion().onOrAfter(Version.V_7_16_0)) {
             out.writeArray((o, order) -> order.writeTo(o), missingOrders);
         }
         out.writeList(buckets);