refactor: remove ApiPluginAAD feature flag and update related logic

[huimiu]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.23%. Comparing base (dc12c6b) to head (077817a).
Report is 1 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #13065      +/-   ##
==========================================
- Coverage   90.23%   90.23%   -0.01%     
==========================================
  Files         583      583              
  Lines       34968    34965       -3     
  Branches     6949     6771     -178     
==========================================
- Hits        31552    31549       -3     
  Misses       1489     1489              
  Partials     1927     1927              

Files with missing lines	Coverage Δ
packages/fx-core/src/common/featureFlags.ts	96.42% <ø> (-0.13%)	⬇️
packages/fx-core/src/question/create.ts	92.06% <100.00%> (-0.02%)	⬇️