Drop typescript-anuglar v16, v17 support (remove samples, tests)

[wing328]

FYI @TiFu (2017/07) @taxpon (2017/07) @sebastianhaas (2017/07) @kenisteward (2017/07) @Vrolijkx (2017/09) @macjohnny (2018/01) @topce (2018/10) @akehir (2019/07) @petejohansonxo (2019/11) @amakhrov (2020/02) @davidgamero (2022/03) @mkusaka (2022/04) @joscha (2024/10) @KannaKim (2026/07)

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

Removes typescript-angular v16 and v17 samples and their CI tests to focus on supported Angular versions and reduce CI time. Updates the workflow to only run v18+ samples.

• Refactors
  • Deleted v16/v17 sample clients and unit tests under samples/client/petstore/... and their configs in bin/configs/.
  • Removed v16/v17 path triggers from .github/workflows/samples-typescript-client.yaml; CI continues for v18–v20 and samples/client/others/typescript-angular.

^{Written for commit 95b7bed. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 112 files

_{Re-trigger cubic}