fix: Delete link events were duplicated when closing the transport

[milyin]

Description

What does this PR do?

It was found that when the Transport is disconnected the LinkEvent message may be duplicated. The PR adds test for this behavior and fixes it

Why is this change needed?

Event duplication is incorrect

Related Issues

The connectivity api was added in #2301
The incorrect behavior was found in z_api_info test in eclipse-zenoh/zenoh-c#1171

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🏷️ Label-Based Checklist

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Labels: bug

🐛 Bug Fix Requirements

Since this PR is labeled as a bug fix, please ensure:

• Root cause documented - Explain what caused the bug in the PR description
• Reproduction test added - Test that fails on main branch without the fix
• Test passes with fix - The reproduction test passes with your changes
• Regression prevention - Test will catch if this bug reoccurs in the future
• Fix is minimal - Changes are focused only on fixing the bug
• Related bugs checked - Verified no similar bugs exist in related code

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.96%. Comparing base (3c77c34) to head (f91c0c5).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2367      +/-   ##
==========================================
+ Coverage   71.91%   71.96%   +0.04%     
==========================================
  Files         390      390              
  Lines       62764    62769       +5     
==========================================
+ Hits        45139    45171      +32     
+ Misses      17625    17598      -27     

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