cli/command: fix flaky TestInitializeFromClientHangs

[hirehamir]

- What I did

Fixed #6003

- How I did it

The test set the client's init timeout to 1 millisecond, then asserted that a request actually reached the fake server.

Under CPU pressure the client goroutine can stall for tens of milliseconds, so the 1 millisecond deadline expires before the request is even written, and the handler never runs.

I raised that timeout to ~500 milliseconds, which is about ~5x the worst stall I measured (40 - 90 milliseconds).

The assertion isn't weakened: the fake server never responds, so the client returning at all still proves the deadline works.

The test's own waits now get a separate 10s backstop instead of sharing the client's 1s context.

Trade-off: the test now waits out the deadline it's testing, so it takes ~500 milliseconds instead of ~2 milliseconds, and cli/command goes from ~0.07s to ~0.57s.

- How to verify it

The flake needs CPU pressure to show up:

systemd-run --user --scope -p CPUQuota=10% \
  ./scripts/with-go-mod.sh go test ./cli/command/ \
  -run TestInitializeFromClientHangs -count=1000 -cpu=1

[codecov-commenter]

Codecov Report

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