fix(tearsheet): resolve focusing elements multiple times while rendering

[makafsal]

Closes #6466

What did you change?

Refactored the TearsheetShell component and removed unwanted focus management

How did you test and verify your work?

yarn avt
yarn test
Storybook

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.84%. Comparing base (473af0f) to head (ecc0147).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6513      +/-   ##
==========================================
+ Coverage   79.65%   79.84%   +0.18%     
==========================================
  Files         394      394              
  Lines       12871    12859      -12     
  Branches     4257     4251       -6     
==========================================
+ Hits        10253    10267      +14     
+ Misses       2618     2592      -26     

Components	Coverage Δ
ibm-products	∅ <ø> (∅)
ibm-products-web-components	∅ <ø> (∅)