Use Gradle-approved exception message prefix for json validation tasks (#66420)

buildSrc/src/main/java/org/elasticsearch/gradle/internal/precommit/ValidateJsonAgainstSchemaTask.java

@@ -124,7 +124,7 @@ public class ValidateJsonAgainstSchemaTask extends DefaultTask {
             sb.append(getReport().toURI().toASCIIString());
             sb.append(System.lineSeparator());
             sb.append(
-                String.format("JSON validation failed: %d files contained %d violations", errors.keySet().size(), errors.values().size())
+                String.format("Verification failed: %d files contained %d violations", errors.keySet().size(), errors.values().size())
             );
             throw new JsonSchemaException(sb.toString());
         }

buildSrc/src/main/java/org/elasticsearch/gradle/internal/precommit/ValidateJsonNoKeywordsTask.java

@@ -171,7 +171,7 @@ public class ValidateJsonNoKeywordsTask extends DefaultTask {
             "Error validating JSON. See the report at: %s%s%s",
             getReport().toURI().toASCIIString(),
             System.lineSeparator(),
-            String.format("JSON validation failed: %d files contained %d violations", errors.keySet().size(), errors.values().size())
+            String.format("Verification failed: %d files contained %d violations", errors.keySet().size(), errors.values().size())
         );
         throw new GradleException(message);
     }