test: increase strictness for test-trace-event

Change test-trace-event such that it checks that all expected values are
within the same trace object rather than scattered across multiple trace
objects.

PR-URL: https://github.com/nodejs/node/pull/11065


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>