Set statusText to "timeout" for 504

[LionNatsu]

statusText = "timeout" when 504 Gateway Timeout occurs

Fixes gh-2932

[mention-bot]

By analyzing the blame information on this pull request, we identified @jaubourg, @gibson042 and @timmywil to be potential reviewers

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[timmywil]

Thanks for the PR, but we've decided not to do this.