HADOOP-16431. Remove useless log in IOUtils.java and ExceptionDiags.java.

This closes #1091

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/IOUtils.java

@@ -508,8 +508,6 @@ public class IOUtils {
       Throwable t = ctor.newInstance(msg);
       return (T) (t.initCause(exception));
     } catch (Throwable e) {
-      LOG.warn("Unable to wrap exception of type " +
-          clazz + ": it has no (String) constructor", e);
       throw exception;
     }
   }

hadoop-tools/hadoop-openstack/src/main/java/org/apache/hadoop/fs/swift/http/ExceptionDiags.java

@@ -91,8 +91,6 @@ public class ExceptionDiags {
       Throwable t = ctor.newInstance(msg);
       return (T) (t.initCause(exception));
     } catch (Throwable e) {
-      LOG.warn("Unable to wrap exception of type " +
-               clazz + ": it has no (String) constructor", e);
       return exception;
     }
   }