RFR: 8320358: GHA: ignore jdk* branches

[Magnus Ihse Bursie]

On Tue, 21 Nov 2023 14:42:07 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> At some point we are likely to use stabilization branches in the mainline jdk repo rather than a separate repo. In preparation, this PR excludes branches matching `jdk*`, like we currently do for `master` and `pr/*`.
> 
> A potential drawback of doing this is that it will exclude developer branches named `jdk-8888888` or similar, using a lower-case `jdk`. Developers who want a GHA run will need to use `JDK` (uppercase) or some other prefix.
> 
> This is unlikely to be a problem in practice. I checked the most recent 100 open pull requests in the `jdk` repo at the time I created this fix, and while many of them use "JDK" (upper case) as a prefix, I found none that use "jdk" (lower case).
> 
> 
> #### Testing
> 
> I pushed the following branch that was even with `jdk:master` at the time I pushed it (thus without this fix). GHA was run as expected:
> 
> * [jdk-8000000](https://github.com/kevinrushforth/jdk/tree/jdk-8000000) : [GHA run](https://github.com/kevinrushforth/jdk/actions/runs/6910232226) (NOTE: once this fix is integrated, such a branch would not get a GHA run)
> 
> 
> I pushed the following branches that all include this fix. GHA runs were skipped on the branches that start with `jdk` and run on the others:
> 
> * [JDK-8320358](https://github.com/kevinrushforth/jdk/tree/JDK-8320358) : [GHA run](https://github.com/kevinrushforth/jdk/actions/runs/6910192534), (you can also see this from this PR's test results)
> * [gha-exclude-jdk](https://github.com/kevinrushforth/jdk/tree/gha-exclude-jdk) : [GHA run](https://github.com/kevinrushforth/jdk/actions/runs/6910204060)
> * [jdk12345](https://github.com/kevinrushforth/jdk/tree/jdk12345) : No GHA run
> * [jdk-8320358-gha](https://github.com/kevinrushforth/jdk/tree/jdk-8320358-gha) : No GHA run

We *could* name the branches `jdk-21` instead or `jdk/21`; I think that would make more sense. However, I still think it is better to be a bit more aggressive here in what we exclude, to open up for more possibilities for us in the future.

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PR Comment: https://git.openjdk.org/jdk/pull/16763#issuecomment-1821174076