Change default SecretLeaseContainer.leaseEndpoints from Legacy to Leases

Closes gh-589.

spring-vault-core/src/main/java/org/springframework/vault/core/lease/SecretLeaseContainer.java

@@ -141,7 +141,7 @@ public class SecretLeaseContainer extends SecretLeaseEventPublisher implements I
 
 	private final KeyValueDelegate keyValueDelegate;
 
-	private LeaseEndpoints leaseEndpoints = LeaseEndpoints.Legacy;
+	private LeaseEndpoints leaseEndpoints = LeaseEndpoints.Leases;
 
 	private Duration minRenewal = Duration.ofSeconds(10);