[Fix](Nereids) change log level of warning of converting error to debug (#29660)

Co-authored-by: libinfeng <libinfeng@selectdb.com>

fe/fe-core/src/main/java/org/apache/doris/nereids/util/TypeCoercionUtils.java

@@ -569,7 +569,7 @@ public class TypeCoercionUtils {
                 }
             }
         } catch (Exception e) {
-            LOG.warn("convert '{}' to type {} failed", value, dataType);
+            LOG.debug("convert '{}' to type {} failed", value, dataType);
         }
         return Optional.ofNullable(ret);