Options, Meta APIs: Add test coverage for update_network_option() c…

…omparison of new and existing value.

Having those tests in `trunk` already will help ensure potential future fixes to this logic maintain backward compatibility.

Props mukesh27, spacedmonkey.
See #59360.


git-svn-id: https://develop.svn.wordpress.org/trunk@56797 602fd350-edb4-49c9-b593-d223f7449a82