[GRADLE-WRAPPER] Generator status message visibility update

[xsveda]

After quite mode implementation in #11211 the build output is shorter but still every generator task logs a single success generation output message:

Successfully generated code to /path/to/output

This PR hides behind the same quiteMode to make the build output clean in case of succesfull run.

PR checklist

• Read the contribution guidelines.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

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Summary by cubic

Make Gradle plugin quiet mode fully quiet by suppressing success and cleanup lifecycle messages. The "Successfully generated code..." and "Cleaned up output directory ..." logs now appear only when quietMode is false, keeping successful builds clean.

^{Written for commit 2918bf6. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}