Clean up items added to match monoservice behavior

All of the following are to be addressed after differential testing is complete. All of these, and some others, are marked with a `@todo('9447')` comment.

1. The dispatch of `pureChecks` was removed to match monoservice behavior. These should be added back in and the end-to-end testing adjusted to match the earlier check for valid transactions (particularly scheduled transactions).
2. The response "BUSY" to transactions with no scheduled transaction (functionality type NONE) should change to something more appropriate (e.g. INVALID_SCHEDULED_TRANSACTION).
3. The duplicate hash calculation and duplicate check should use calculated expiration rather than just provided expiration. (c.f. report #2241878)
4. The non-validation of the account that creates a scheduled transaction as payer for the child transaction should be changed
5. The removal of previously validated (but not currently required) keys should be changed to retain all previously validated keys.

Begin by completing differential testing, then search for every `@todo('9447')` comment and inspect the related transaction and end-to-end tests. Done means all five listed behavior differences are addressed, including pureChecks dispatch, the NONE response, expiration-based duplicate handling, payer validation, and retention of previously validated keys.

Written by the indexing model from the issue text.