refs: mark invalid refname message for translation

refs: mark invalid refname message for translation

The error message produced by `transaction_refname_valid()` changes based
on whether the update is a ref update or a reflog update, with the use
of a ternary operator. This breaks translation since the sub-msg is not
marked for translation. Fix this by setting the entire message using a
`if {} else {}` block and marking each message for translation.

Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>