Jsr223ScriptEvaluator: initialization log on INFO and only if not null

It's better to know when the script engine is also initialized, it's
a single log during startup, now on INFO level.
Also, previously (DEBUG) it was printed also when NOT initialized.

model/model-common/src/main/java/com/evolveum/midpoint/model/common/expression/script/jsr223/Jsr223ScriptEvaluator.java

@@ -42,11 +42,12 @@ public Jsr223ScriptEvaluator(String engineName, PrismContext prismContext,
         ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
         long initStartMs = System.currentTimeMillis();
         scriptEngine = scriptEngineManager.getEngineByName(engineName);
-        LOGGER.debug("Script engine for '{}' initialized in {} ms.",
-                engineName, System.currentTimeMillis() - initStartMs);
         if (scriptEngine == null) {
             LOGGER.warn("The JSR-223 scripting engine for '" + engineName + "' was not found");
+            return;
         }
+        LOGGER.info("Script engine for '{}' initialized in {} ms.",
+                engineName, System.currentTimeMillis() - initStartMs);
     }
 
     @Override