Re: Schema variables - new implementation for Postgres 15

- For sessionvariable.c (in 0002), I see that there are still all the comments
  and code about checking type validity based on a generation number and other
  heuristics.  I still fail to understand why this is needed at all as the
  stored datum should remain compatible as long as we prevent the few
  incompatible DDL that are also prevented when there's a relation dependency.
  As an example, I try to quickly disable all that code with the following: