Reenable Bwc Tests After #52557 (#52623)

Now that #52557 has been merged we can reenable BwC tests.

build.gradle

@@ -216,8 +216,8 @@ task 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/52557" /* 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/cluster/SnapshotsInProgress.java

@@ -57,7 +57,7 @@ import static org.elasticsearch.snapshots.SnapshotInfo.METADATA_FIELD_INTRODUCED
  */
 public class SnapshotsInProgress extends AbstractNamedDiffable<Custom> implements Custom {
 
-    private static final Version VERSION_IN_SNAPSHOT_VERSION = Version.V_8_0_0;
+    private static final Version VERSION_IN_SNAPSHOT_VERSION = Version.V_7_7_0;
 
     public static final String TYPE = "snapshots";