[Improve][Config] Add warning for use fall back keys (#5753)

Author: Hisoka-X

seatunnel-api/src/main/java/org/apache/seatunnel/api/configuration/ReadonlyConfig.java

@@ -103,10 +103,10 @@ public <T> Optional<T> getOptional(Option<T> option) {
             for (String fallbackKey : option.getFallbackKeys()) {
                 value = getValue(fallbackKey);
                 if (value != null) {
-                    log.info(
-                            "Config uses fallback configuration key '{}' instead of key '{}'",
-                            fallbackKey,
-                            option.key());
+                    log.warn(
+                            "Please use the new key '{}' instead of the deprecated key '{}'.",
+                            option.key(),
+                            fallbackKey);
                     break;
                 }
             }