FIX/McpWorkbench_errors_properties_and_grace_shutdown

[SongChiYoung]

Why are these changes needed?

Our McpWorkbench required properties however mongodb-lens's some tools do not has it. I will fix it from when properties is None, -> {}
Our McpWorkbench now does not have stop routine with without async with McpWorkbench(params) as workbench: and lazy init. So, I will adding def del: pass just insert that, It could show error.

Related issue number

Closes #6425

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.57%. Comparing base (6fc4f53) to head (71b8f97).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6444      +/-   ##
==========================================
+ Coverage   78.55%   78.57%   +0.02%     
==========================================
  Files         225      225              
  Lines       16523    16525       +2     
==========================================
+ Hits        12979    12984       +5     
+ Misses       3544     3541       -3     

Flag	Coverage Δ
unittests	78.57% <100.00%> (+0.02%)	⬆️

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