test: fix flaky test-regress-GH-897

Even after being moved to `sequential` in
1ce05ad5, `test-regress-GH-897` still
was occasionally flaky on Raspberry Pi devices on CI.

The test is especially sensitive to resource constraints. It failed
reliably on my laptop if I moved it to `parallel` and ran 32 competing
node test processes. Even for a flaky test, that's unusually low. I
typically don't see problems, even for flaky tests, until I get up to
around four times that number.

On a Raspberry Pi, of course, that sensitivity to resource constraints
will manifest much sooner.

This change checks the order of timers firing, rather than the duration
before a timer is fired. This eliminates the sensitivity to resource
constraints. The test can now be moved back to `parallel`. I am able to
run many copies of the test simultaneously without seeing test failures.

PR-URL: https://github.com/nodejs/node/pull/10903
Fixes: https://github.com/nodejs/node/issues/10073


Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>