refactor(core): switch logging of utils method to trace

- Do not log all additional UES during the synchronization
  in DEBUG, switch it to TRACE. We should have other means
  for tracking running synchronization.

perun-core/src/main/java/cz/metacentrum/perun/core/impl/Utils.java

@@ -217,7 +217,7 @@ public static List<RichUserExtSource> extractAdditionalUserExtSources(PerunSessi
 
 				// Entry contains extSourceName|extSourceType|extLogin;uesAttribute=value1,value2[|LoA]
 				String[] userExtSourceRaw =  subjectFromExtSource.get(attrName).split("\\|");
-				log.debug("Processing additionalUserExtSource {}",  subjectFromExtSource.get(attrName));
+				log.trace("Processing additionalUserExtSource {}",  subjectFromExtSource.get(attrName));
 
 				// Check if the array has at least 3 parts, this is protection against outOfBoundException
 				if(userExtSourceRaw.length < 3) {