Fix: silence backward switch default warning (backport #3203)

[mergify]

🦟 Bug fix

Fixes #3202

Summary

As the switch are using dwarf_tags to handle the case, I think it could dissable the compilation -Wno-switch-default as it was already evaluating the cases, so no need of a deefault clause

To replicate this behaviour follow this steps:

1. Go to https://build.osrfoundation.org/job/gz_sim-ci-gz-sim8-jammy-amd64 or https://build.osrfoundation.org/job/gz_sim-ci-gz-sim8-noble-amd64
2. Build the job
3. See the gcc warning

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers
• Was GenAI used to generate this PR? If so, make sure to add "Generated-by" to your commits. (See this policy for more info.)

  ---

  This is an automatic backport of pull request Fix: silence backward switch default warning #3203 done by Mergify.

[mergify]

Cherry-pick of 5318644 has failed:

On branch mergify/bp/gz-sim9/pr-3203
Your branch is up to date with 'origin/gz-sim9'.

You are currently cherry-picking commit 53186440.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   test/CMakeLists.txt

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   test/backward_vendor/backward-cpp/CMakeLists.txt

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[scpeters]

Cherry-pick of 5318644 has failed:

I resolved the conflicts manually, amended and force-pushed to 1db1c8a