Fix a Couple bugs related to pivot exports (#48867)

* Fix a Couple bugs related to pivot exports

 - pivot-grouping value, when not an int (in the case of Oracle dbs), would cause exports to contain zero rows. This
 fixes that
 - json formatted/unformatted for the dataset API endpoints (unsaved questions) was not being used, so all exports
 were formatted

* json and csv use (int group) to check row inclusion

* grouping change fix tests

* json formatted/unformatted test

* xlsx formatters are correct when pivot-grouping col is removed

* cljfmt

* fix up failing tests

* fix test

* Update src/metabase/api/dataset.clj