[BUG][Java][Spring] Generated code fails Error Prone UnnecessaryFinal bug pattern

[anthonyvdotbe]

Fixes #24744

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

Remove redundant final modifiers from constructor parameters in generated Spring HTTP interface configurators. This eliminates Error Prone UnnecessaryFinal warnings without changing runtime behavior.

• Update templates httpInterfacesConfiguration.mustache and httpServiceProxyFactoryInterfacesConfigurator.mustache in the JavaSpring spring-http-interface library.
• Regenerate affected samples to reflect the change.
• No migration required; output differs only by parameter modifiers and compiles the same.

^{Written for commit c7f14f8. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 11 files

_{Re-trigger cubic}