[Serve] Add more nuanced checks for http proxy status errors

[Superskyyy]

Closes: https://github.com/ray-project/ray/issues/47895

Why are these changes needed?

Related issue number

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• [x] I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• [ ] I've run scripts/format.sh to lint the changes in this PR.
• [ ] I've included any doc changes needed for https://docs.ray.io/en/master/.
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• [ ] I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • [ ] Unit tests
  • [ ] Release tests
  • [ ] This PR is not tested :(

[Superskyyy]

Thanks for the contribution!

Could you please also add an e2e test for this behavior to test_metrics.py? You should be able to follow other tests there as a blueprint.

Certainly, I will do that. Thanks

[edoakes]

Hey @Superskyyy just checking in, let me know if you need a pointer on the test

[edoakes]

@Superskyyy just checking in again, I can take over adding the required test if you don't have time