Streamline deployment.yml

[koppor]

This ports the non-related changes of #10867 to the main workflow.

Having the Gradle Daemon running on CI is now considered good practice (e.g., gradle/gradle#2824). Thus, I reenable the gradle daemon.

Furthermore, I remove unused variables (and add a comment)

Mandatory checks

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[github-actions]

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