If the transaction fails during replay because of certification
failure, the provider will return control to applier without
terminating the transaction and transaction remains in
s_replaying.
Fixed transaction::after_statement() to handle the state changes
correctly if certification failure is returned from replay.
Replaying was extracted to separate private method from
after_statement(). Removed transaction::after_replay() as it
seems now unnecessary and it bypassed state change sanity checks.
Allowed replaying -> committed transaction transition to handle
the situation where DBMS allocates a new context and client_state
to do the replay.