fix: deprecate spfx-productivity-dashboard sample e2e test

[qfai]

Because the sample is deprecated, should delete the e2e test too.
Deprecate PR: OfficeDev/microsoft-365-agents-toolkit-samples#1552

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.24%. Comparing base (fb67669) to head (2d2c82f).
⚠️ Report is 4 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev   #15138   +/-   ##
=======================================
  Coverage   89.23%   89.24%           
=======================================
  Files         618      618           
  Lines       37993    37993           
  Branches     7510     7518    +8     
=======================================
+ Hits        33903    33905    +2     
+ Misses       1973     1972    -1     
+ Partials     2117     2116    -1     

see 2 files with indirect coverage changes

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