Convert most use sites from `co_return coroutine::make_exception`
to `co_await coroutine::return_exception{,_ptr}` where possible.
In cases this is done in a catch clause, convert to
`co_return coroutine::exception`, generating an exception_ptr
if needed.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Closes#10972
acae3cc223