PipelinePerfTest - add test for idle state numbers

[cijothomas]

Runs for few seconds only to avoid taking up perf test machine.
This test maybe okay to be run in normal GH runners and we can run for more duration. For future considerations...

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.19%. Comparing base (9b0aa84) to head (a2394de).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1740      +/-   ##
==========================================
- Coverage   84.20%   84.19%   -0.01%     
==========================================
  Files         473      473              
  Lines      137454   137454              
==========================================
- Hits       115746   115736      -10     
- Misses      21174    21184      +10     
  Partials      534      534              

Components	Coverage Δ
otap-dataflow	85.47% <ø> (-0.02%)	⬇️
query_abstraction	80.61% <ø> (ø)
query_engine	90.53% <ø> (ø)
syslog_cef_receivers	∅ <ø> (∅)
otel-arrow-go	53.50% <ø> (ø)

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