Issue: It looks like Range header end value was constructed by adding chunk size to
current position. This leads into the request being one byte longer, and also
the received response body is one byte longer than anticipated.

Fix: adjust the end to be one byte earlier.

For example with `chunksize=1024` and current position being 0, the range header
should be set to `bytes=0-1023`.

See: https://httpwg.org/specs/rfc7233.html#rule.ranges-specifier

Resolves: googleapis#1593