[#25501] Stabilize flaky Fast DDS Spy Windows application tests in CI

[Danipiza]

Description

This PR reduces flakiness in the Fast DDS Spy application tests on Windows CI.

GitHub Actions on windows-2022 was showing flaky failures in Fast DDS Spy application tests that do not reproduce reliably locally. The failures were concentrated in DDS discovery-dependent one-shot tests

Changes

• Add a short startup delay before launching the spy when DDS publisher-based tests are used
• Increase the shared discovery time used by DDS-backed application tests
• Normalize empty CLI output so '' and '\n' are treated equivalently
• Improve one-shot test diagnostics by printing stderr on timeout

Branch closed

I have close the Fast-DDS-Spy PR and reopen this one because the name of the branch was related with the ci/execute-toolsbranch (DDS-Pipe PR) and the PR in DDS-Pipe that solve flaky tests have this branch name (fix/flaky_tests)

[codecov]

Codecov Report

❌ Patch coverage is 78.57143% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.59%. Comparing base (1c51730) to head (cb4d0f6).

Files with missing lines	Patch %	Lines
fastddsspy_tool/src/cpp/tool/Controller.cpp	78.57%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #154      +/-   ##
==========================================
- Coverage   62.82%   58.59%   -4.23%     
==========================================
  Files          29       28       -1     
  Lines        2480     1942     -538     
  Branches     1068      773     -295     
==========================================
- Hits         1558     1138     -420     
+ Misses        363      323      -40     
+ Partials      559      481      -78     

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.