Do not expect a 200 HTTP status code when updating a share

This will be needed to test scenarios in which updating a share return a
different HTTP status code, like 401.

The assertion for the 200 HTTP status code was added in those scenarios
that tested updating a share (that is, those that were also checking the
OCS status code), but not in those in which updating a share was just a
preparatory step for the actual test (in the same way that the HTTP
status code is not checked in those tests when creating a share).

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>