Fix parallel create-testnet-data stdout contents test

[carbolymer]

Changelog

- description: |
    Fix parallel `create-testnet-data` stdout contents test 
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - improvement    # QoL changes e.g. refactoring
  # - bugfix         # fixes a defect
   - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

This PR fixes this test failure: https://github.com/IntersectMBO/cardano-cli/actions/runs/8201716507/job/22431021627?pr=637#step:14:59
Which got introduced in #637, which got accidentally merged.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[Jimbo4350]

👍

[Jimbo4350]

Why always use with NOINLINE?

[carbolymer]

Otherwise GHC could inline the semaphore, and instead of one we could end up with multiple, different semaphores not communicating with each other. So the locking wouldn't work.