Deprecate `GetOmapValues` in favour of `GetOmapValuesOrdered`

> If we deprecate we can consider removing it in the future. That lowers our "surface area" that we need to maintain. Plus converting to a map is like 3 lines. So I prefer deprecation but I won't require it for approval.

Fair enough. Since _GetOmapValuesOrdered_/_GetAllOmapValuesOrdered_ are being introduced as preview APIs, I think it's premature to deprecate _GetOmapValues_ in favour of something that isn't stable yet. I hope we create an issue similar to https://github.com/ceph/go-ceph/issues/1306 in this case.

_Originally posted by @anoopcs9 in https://github.com/ceph/go-ceph/issues/1326#issuecomment-5481676908_

Start by locating the GetOmapValues, GetOmapValuesOrdered, and GetAllOmapValuesOrdered APIs and review their current status. Resolve whether the preview APIs are stable enough for deprecation; done means the chosen deprecation direction is reflected consistently in the Go bindings and its supporting checks.

Written by the indexing model from the issue text.