Remove zero padding from the key in the range index

[raminqaf]

Currently, we are padding the key of the topic with zeros and creating the range index. This is not needed. It is sufficient to zero-pad the value and concatenate the key with the value for the range index.
This will remove the type limitation of the key. Now the key should be only an integer or long. But after removing the zero padding, the key can also be a string.