`pkg/dds/test/dap/integration/debug_test` went from flaky -> Timeout

[derekxu16]

pkg/dds/test/dap/integration/debug_test went from flaky -> Timeout on unittest-asserts-release-mac-arm64

https://dart-ci.appspot.com/log/pkg-mac-release-arm64/unittest-asserts-release-mac-arm64/16606/pkg/dds/test/dap/integration/debug_test

@DanTup

[alexmarkov]

pkg/dds/test/dap/integration/debug_test turned flaky -> Timeout once again:

https://dart-ci.appspot.com/log/pkg-mac-release-arm64/unittest-asserts-release-mac-arm64/16762/pkg/dds/test/dap/integration/debug_test

[DanTup]

This looks like the same error reported at #60221:

<== [DAP] {"seq":5,"type":"response","command":"launch","request_seq":3,"success":true}
<== [DAP] {"seq":6,"type":"event","body":{"category":"stderr","output":"Could not start the VM service:\n"},"event":"output"}
<== [DAP] {"seq":7,"type":"event","body":{"category":"stderr","output":"\n"},"event":"output"}

I suspect the timeout is because when this happens, the service-info file is never written (and we sit waiting for it, because that's how we get the VM Service URI to connect to). It seems like the process never terminates in this state (if it did, I think we'd see an immediate failure and not a timeout).

(Edit: I've filed #60256 about the VM not terminating)