log actual error message instead of 'Exception during pool'

name 'PoolInitializationException' is descriptive enough

src/main/java/com/zaxxer/hikari/pool/PoolInitializationException.java

@@ -31,6 +31,6 @@ public class PoolInitializationException extends RuntimeException
     */
    public PoolInitializationException(Throwable t)
    {
-      super("Exception during pool initialization", t);
+      super(t);
    }
 }