🤖 tests: editCancelKeepsDraft repro failed once on phone (draft empty after Cancel) #5876

The bug-bash repro tests/bugbash/repros/editCancelKeepsDraft.e2e.ts failed once on the phone target, in the merge-group run https://github.com/coder/xum/actions/runs/37763109369 (job "Test / E2E (linux 1/4)", for #5875):

FAIL  phone  repros/editCancelKeepsDraft.e2e.ts > Cancel in edit mode leaves edit mode and keeps the unsent draft
ASSERTION_FAILED: expect.toHaveValue failed
locator: getByRole("textbox", name: "Message")
expected: value "unsent draft"
observed: value "" (match count 1)
 ❯ repros/editCancelKeepsDraft.e2e.ts:28:5

The same tree passed this shard on the PR run (https://github.com/coder/xum/actions/runs/37761591117). #5875 changes only tests/bugbash/sandbox/, and no repro imports those files. The failure is intermittent. It has two possible causes: a real intermittent loss of the draft when edit mode is cancelled at phone width, or a timing gap in the repro (the value check right after toBeHidden). I did not reproduce it locally. Among the 20 most recent failed pr.yml runs, only this run shows the failure.

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