Fix delete image tests.

Add wait until checkbox is in active state.

Fix edit_image_description_and_name test.
Add wait until the name text box is filled by default name (is not empty).
In the other case selenium write new name into text box faster than default
name is written there so default name then rewrite the new name.

Change-Id: I56803e19dd80180cc432ca872a28a7ee7f41290d
(cherry picked from commit I56803e19dd80180cc432ca872a28a7ee7f41290d)