Remove static checks for serialization size

[cjnolet]

This PR removes static checks for serialization size. Upstream changes like rapidsai/rmm#1370 have altered these sizes and break RAFT CI. An alternative approach to verifying serialization will be developed.

[bdice]

There are more places to fix in cagra_serialize.cuh:

  /home/coder/raft/cpp/include/raft/neighbors/detail/cagra/cagra_serialize.cuh(40): error: static assertion failed with "The size of the index struct has changed since the last update; paste in the new size and consider updating the serialization logic"
            detected during instantiation of class "raft::neighbors::cagra::detail::check_index_layout<RealSize, ExpectedSize> [with RealSize=216UL, ExpectedSize=200UL]" 

Also I believe the serialization version is expected to increment every time this changes. See #1964 for an example of the changes we'll need.

[cjnolet]

/merge

[harrism]

Thanks for removing these checks. Will make life easier upstream.