👨‍🌾 PeerTracker.PeerTrackerStale test flaky on MacOS + Citadel

[Blast545]

Environment

• OS Version: homebrew-amd64 buildfarm
• Source, gz-gazebo3

Reference failures: https://build.osrfoundation.org/job/ignition_gazebo-ci-ign-gazebo3-homebrew-amd64/223/
https://build.osrfoundation.org/job/ignition_gazebo-ci-ign-gazebo3-homebrew-amd64/221/
https://build.osrfoundation.org/job/ignition_gazebo-ci-ign-gazebo3-homebrew-amd64/216/

Error Message
/Users/jenkins/workspace/ignition_gazebo-ci-ign-gazebo3-homebrew-amd64/ign-gazebo/src/network/PeerTracker_TEST.cc:178
Expected equality of these values:
  1
  stalePeers
    Which is: 2
Stacktrace
/Users/jenkins/workspace/ignition_gazebo-ci-ign-gazebo3-homebrew-amd64/ign-gazebo/src/network/PeerTracker_TEST.cc:178
Expected equality of these values:
  1
  stalePeers
    Which is: 2

Description

• Expected behavior: Test Passes
• Actual behavior: Sometimes it fails on MacOS

Steps to reproduce

1. Run a buildfarm job on gz-gazebo + MacOS
2. Repeat 1 until the error shows up

Output

See: https://build.osrfoundation.org/job/ignition_gazebo-ci-ign-gazebo3-homebrew-amd64/223/testReport/junit/(root)/PeerTracker/PeerTrackerStale/

[Blast545]

Duplicated from #760