[jfx21u] RFR: 8314484: Update Gradle to 8.4 [v2]

[Kevin Rushforth]

On Mon, 30 Oct 2023 17:44:01 GMT, Ambarish Rapte <arapte at openjdk.org> wrote:

>> Clean backport to jfx21.
>> Verified a build locally on macOS.
>
> Ambarish Rapte has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Empty commit

All looks good. And I see a clean GHA run now.

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Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx21u/pull/22#pullrequestreview-1704779440