LoggingBunyan: should write diagnostic entry failed

[flaky-bot]

Note: #665 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

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commit: 72438bd
buildURL: Build Status, Sponge
status: failed

Test output

Timeout of 90000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (/workspace/build/system-test/logging-bunyan.js)
Error: Timeout of 90000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves. (/workspace/build/system-test/logging-bunyan.js)
    at listOnTimeout (internal/timers.js:554:17)
    at processTimers (internal/timers.js:497:7)

[flaky-bot]

Looks like this issue is flaky. 😟

I'm going to leave this open and stop commenting.

A human should fix and close this.

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When run at the same commit (72438bd), this test passed in one build (Build Status, Sponge) and failed in another build (Build Status, Sponge).