During some refactoring I noticed that the field
IndexInfo.ii_OpclassOptions is kind of useless. The IndexInfo struct is
notionally an executor support node, but this field is not used in the
executor or by the index AM code. It is really just used in DDL code in
index.c and indexcmds.c to pass information around locally. For that,
it would be clearer to just use local variables, like for other similar
cases. With that change, we can also remove
RelationGetIndexRawAttOptions(), which only had one caller left, for
which it was overkill.