Update to Gradle 9.4.1

[wmdietl]

I leave enabling the gradle configuration cache for #1362.

[Copilot]

Pull request overview

Updates the repository’s Gradle wrapper to Gradle 9.4.1 and adjusts build scripts/wrapper scripts to align with wrapper changes and Gradle 9 behavior.

Changes:

• Bump Gradle wrapper distribution from 8.14.4 to 9.4.1 (properties + wrapper jar) and regenerate wrapper scripts.
• Update Spotless configuration to use predeclareDeps() and modernize some dependency notations.
• Adjust build logic for checker assembly and test suite reporting to work cleanly with the updated Gradle version.

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
gradlew.bat	Removes explicit CLASSPATH handling and runs wrapper via -jar.
gradlew	Wrapper script regeneration aligned with the new wrapper behavior (no explicit CLASSPATH usage).
gradle/wrapper/gradle-wrapper.properties	Points wrapper distribution URL to Gradle 9.4.1.
gradle/wrapper/gradle-wrapper.jar	Updates wrapper implementation jar to match the new Gradle version.
checker/build.gradle	Changes assemble wiring to depend on jar-producing tasks without using deprecated archives artifact wiring.
build.gradle	Spotless predeclare API update; dependency notation tweaks; replaces afterSuite {} with an explicit TestListener.

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