RFR: 8342576: [macos] AppContentTest still fails after JDK-8341443 for same reason on older macOS versions

[Christoph]

On Fri, 25 Oct 2024 01:49:01 GMT, Alexander Matveev <almatvee at openjdk.org> wrote:

> - It is not clear on which macOS versions codesign fails if application bundle contains additional content.
> - As a result test was modified to generate only application image, since PKG or DMG cannot be generated if signing fails. Exit code of jpackage is ignored, but generated application image will be checked for additional content.
> - This change is for macOS only.
> - Previous implementation of test (forcing expected exist code to 1) was not doing anything useful, since we never checked if additional content was copied or not.

>From the GitHub actions run with double signing:  (mac os 14 runner) 
jpackage Log starts at `Creating app package: JabRef.app`

[signed_image_signed_dmg_macOS (ARM64) installer and portable version.txt](https://github.com/user-attachments/files/20016626/signed_image_signed_dmg_macOS.ARM64.installer.and.portable.version.txt)

Run with only signing the pkg/dmg: 
[only signing dmg_macOS (ARM64) installer and portable version.txt](https://github.com/user-attachments/files/20016647/only.signing.dmg_macOS.ARM64.installer.and.portable.version.txt)

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PR Comment: https://git.openjdk.org/jdk/pull/21698#issuecomment-2847804315