Fix output of bin/generate-samples.sh in tmux

[stephenfin]

Commit 23dae2b reworked this script to start capturing exceptions but the mechanism used was crude and broke output on tmux, since /dev/pts/0 is hardcoded to a specific pseudo-terminal but each tmux pane gets its own pts. Rework this to use files instead.

While here, we also align some indentation with the rest of the file and remove a sleep statement that has been commented out for a few years.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• 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.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• 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

Fix generate-samples.sh output in tmux by logging to a temp file instead of /dev/pts/0. The script now correctly detects exceptions and non-zero exit codes.

• Bug Fixes
  • Use mktemp + tee for output and clean up via trap, which works across tmux panes.
  • Check PIPESTATUS for the Java process and grep the log for “exception” to fail reliably.
  • Remove the stale “press CTRL+C” sleep warning.

^{Written for commit 588b3a9. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

[stephenfin]

@wing328 Looks like 3be911d tagged the wrong issue ID? Could you reopen this, assuming it make sense?