fix: remove the message-extension-copilot template

[huimiu]

https://msazure.visualstudio.com/Microsoft%20Teams%20Extensibility/_workitems/edit/30668746

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.23%. Comparing base (dc12c6b) to head (ef4f021).
Report is 1 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #13067      +/-   ##
==========================================
- Coverage   90.23%   90.23%   -0.01%     
==========================================
  Files         583      583              
  Lines       34968    34965       -3     
  Branches     6949     6783     -166     
==========================================
- Hits        31552    31549       -3     
  Misses       1489     1489              
  Partials     1927     1927              

see 2 files with indirect coverage changes