test: minor cleanup to pino ESM test

[trentm]

The ESM tests are out of process so the setup done in
setupInstrumentationAndInitTestContext() isn't relevant.

[trentm]

@JamieDanielson poke, because you were last editing this test code. (I'm working on adding Logs Bridge support to instr-pino. I wanted to get this minor tweak in separate from my coming PR.)

No rush. I won't have my instr-pino Logs Bridge PR ready until next week.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.38%. Comparing base (dfb2dff) to head (0d5cc8f).
Report is 142 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2241      +/-   ##
==========================================
- Coverage   90.97%   90.38%   -0.60%     
==========================================
  Files         146      148       +2     
  Lines        7492     7509      +17     
  Branches     1502     1573      +71     
==========================================
- Hits         6816     6787      -29     
- Misses        676      722      +46     

see 44 files with indirect coverage changes