[#566] Fix event based comm cxx example

[elfenpiff]

Inconsistent history requirements lead to a connection failure when the subscriber was created first.

Notes for Reviewer

Pre-Review Checklist for the PR Author

• Add sensible notes for the reviewer
• PR title is short, expressive and meaningful
• Consider switching the PR to a draft (Convert to draft)
  • as draft PR, the CI will be skipped for pushes
• Relevant issues are linked in the References section
• Every source code file has a copyright header with SPDX-License-Identifier: Apache-2.0 OR MIT
• Branch follows the naming format (iox2-123-introduce-posix-ipc-example)
• Commits messages are according to this guideline
  • Commit messages have the issue ID ([#123] Add posix ipc example)
  • Commit author matches Eclipse Contributor Agreement(and ECA is signed)
• Tests follow the best practice for testing
• Changelog updated in the unreleased section including API breaking changes
• Assign PR to reviewer
• All checks have passed (except task-list-completed)

Checklist for the PR Reviewer

• Commits are properly organized and messages are according to the guideline
• Unit tests have been written for new behavior
• Public API is documented
• PR title describes the changes

Post-review Checklist for the PR Author

• All open points are addressed and tracked via issues

References

Closes #566

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.31%. Comparing base (3526a25) to head (97aff93).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #567      +/-   ##
==========================================
+ Coverage   79.30%   79.31%   +0.01%     
==========================================
  Files         203      203              
  Lines       25230    25230              
==========================================
+ Hits        20008    20011       +3     
+ Misses       5222     5219       -3     

see 8 files with indirect coverage changes