test: TestNICIRQReportAddsNoLoop1036 can read the log before Listen logs 'listening' (start909 returns on the published address) #1108

TestNICIRQReportAddsNoLoop1036 (internal/engine/epoll) failed in CI twice (the first CI run of PR #1106 and attempt 2 of PR #1105's Coverage): the start909 helper returns as soon as the engine has published its address, but Listen logs "listening" after that, so the test can read the log before the line is there.

Fix: celeris draft PR #1106 makes start909 return only once the listening line is logged, with a failing-first test (TestStart909ReturnsOnlyOnceTheListeningLineIsLogged: 5 of 5 red before, 30 of 30 green after). The test exercises the helper's ordering; no natural reproduction was seen locally (0 of 100). Found while triaging the CI flakes of PR #1105.