Release stabilization: Create backport issues immediately

[Mark Reinhold]

2023/12/13 10:44:52 -0500, pavel.rappo at oracle.com:
> One disadvantage of the proposed adjustment I see is the need to
> create a JBS backport issue manually. (Unless I'm mistaken.) Not that
> it's difficult, but it's error-prone. In contrast, when using Skara
> /backport command, the JBS backport issue is created automatically.
> 
> Why can't we just _forward port_ an issue to the main-line using the
> same Skara /backport command, but with the benefits of automation? Fix
> your issue in the stabilisation repo first and then forward port it to
> the main-line. In this case, you don't even need any additional
> approvals, right? Unless, of course, people object to having
> "Backport-of" commits in the main-line repo. (Speaking of which, we
> already have 25 of such commits there.)

That’s (roughly) what we used to do, and it wasn’t working terribly
well, which is why Erik proposed the backport-from-main-line model
that we discussed and adopted as of JDK 21.

- Mark