test: only assert on first lines of TLS trace
The TLS trace data is best-effort, and enough can be dropped from pipe buffers that only the start of the trace is detected. Only assert on the first line of the trace, it should not get dropped, and it's enough to check that trace was enabled via CLI.
Fixes: https://github.com/nodejs/node/issues/27636
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines