Finally we have some auto-generated documentation for the supported values of transaction.search objectType.
This is useful since we have 70+ of them, and they are totally obscure to newcomers (and us, core team, lol).
The already-existing exception messages now do not suggest anymore values that exist but are not supported (e.g. XACT).
Moreover, we handle an unmanaged exception in transaction.search, when the existing `objectType` is not supported (e.g. XACT).
Closes T16054