fix(template): remote preview

[tecton]

1. Update environment variables corresponding to user managed identity in appsettings.
   • Test Tool will overwrite and use client secret auth type.
2. Remove Test Tool support in notification bot templates until anonymous auth is supported by Agents SDK.

Related bugs:

• https://msazure.visualstudio.com/Microsoft%20Teams%20Extensibility/_workitems/edit/32032482
• https://msazure.visualstudio.com/Microsoft%20Teams%20Extensibility/_workitems/edit/32019771

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.38%. Comparing base (b943acc) to head (6759551).
Report is 3 commits behind head on release/VS1714P3.

Additional details and impacted files

@@                Coverage Diff                @@
##           release/VS1714P3   #13570   +/-   ##
=================================================
  Coverage             90.38%   90.38%           
=================================================
  Files                   623      623           
  Lines                 37461    37461           
  Branches               7395     7469   +74     
=================================================
  Hits                  33860    33860           
  Misses                 1542     1542           
  Partials               2059     2059           

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