test: Fix `common.PIPE` to be process unique
- Fix
common.PIPE
to be process unique - tiny bit of refactoring in adjacent lines
Fixes: https://github.com/nodejs/node/issues/14128
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines
Affected core subsystem(s)
test,stream,net