This PR reverts the scylla sstable schema loading improvements as they fail in CI every other run. I am already working on fixes for these but I am not sure I understand all the failures so it is best to revert and re-post the series later.
Fixes: #13404Fixes: #13410Closes#13419
* github.com:scylladb/scylladb:
Revert "Merge 'tool/scylla-sstable: more flexibility in obtaining the schema' from Botond Dénes"
Revert "tools/schema_loader: don't require results from optional schema tables"