[Humble] Add sleep in setup of flaky PSM test fixture

[sea-bass]

Description

This is the Humble version of #3124, in which the test was never disabled and continued to be flaky.

See my log of successful retries: https://github.com/moveit/moveit2/actions/runs/11966024737?pr=3126

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

[mergify]

Please target the main branch for development, we will backport the changes to humble for you if approved and if they don't break API.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.28%. Comparing base (ccf7e5c) to head (9d03c90).
Report is 17 commits behind head on humble.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           humble    #3126      +/-   ##
==========================================
- Coverage   51.15%   42.28%   -8.87%     
==========================================
  Files         382      668     +286     
  Lines       31902    57743   +25841     
  Branches        0     7323    +7323     
==========================================
+ Hits        16317    24411    +8094     
- Misses      15585    33147   +17562     
- Partials        0      185     +185     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[TSNoble]

@sea-bass

Could we replace the sleep with waitForService call(s)? Additionally, could we keep the issue open, since this is more of a workaround than a fix of the race condition?

[sjahr]

@sea-bass

Could we replace the sleep with waitForService call(s)? Additionally, could we keep the issue open, since this is more of a workaround than a fix of the race condition?

👍 Let's merge this workaround for now and keep the issue open until it is properly solved

[sea-bass]

@sea-bass

Could we replace the sleep with waitForService call(s)? Additionally, could we keep the issue open, since this is more of a workaround than a fix of the race condition?

This is a good idea. I truly wonder what it is about the planning scene that makes this happen. Maybe getting a full robot description topic?