Remove AUTOINITIALIZE env variable

[jonathangreen]

Description

Since importing app no longer automatically initializes anything, we are able to clean up this conditional code.

Motivation and Context

Nice to not have our tests rely on env variables be set. After #1817 goes in, i believe there aren't any more environment variables we depend on to change test initialization.

How Has This Been Tested?

Running tests.

Checklist

• I have updated the documentation accordingly.
• All new and existing tests passed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.05%. Comparing base (81c439c) to head (8b7c6bf).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1824      +/-   ##
==========================================
+ Coverage   90.03%   90.05%   +0.01%     
==========================================
  Files         299      299              
  Lines       39543    39541       -2     
  Branches     8588     8588              
==========================================
+ Hits        35603    35609       +6     
+ Misses       2613     2606       -7     
+ Partials     1327     1326       -1     

Flag	Coverage Δ
manager	89.85% <100.00%> (+0.01%)	⬆️
migration	24.53% <0.00%> (+<0.01%)	⬆️

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