revert: docs: Add TypeScript typings to LmsApiService group methods

[marlonkeating]

This change reverts #1426 pending investigation of why group creation is failing with that change.

Testing Instructions

• Go to the admin-portal repo, pull down branch, and run npm run start:stage
• Navigate to https://localhost.stage.edx.org:1991/alc-general/admin/people-management
• Click 'Create group'
• Add name, members, and click 'Create'
• Verify group is created with learners populated and no error messages

For all changes

• Ensure adequate tests are in place (or reviewed existing tests cover changes)

Only if submitting a visual change

• Ensure to attach screenshots
• Ensure to have UX team confirm screenshots

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.48%. Comparing base (d5fef09) to head (3b0ca28).

Files with missing lines	Patch %	Lines
src/data/services/LmsApiService.js	70.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1432      +/-   ##
==========================================
+ Coverage   86.43%   86.48%   +0.05%     
==========================================
  Files         660      660              
  Lines       14931    14936       +5     
  Branches     3171     3164       -7     
==========================================
+ Hits        12905    12917      +12     
+ Misses       1956     1952       -4     
+ Partials       70       67       -3     

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[marlonkeating]

No longer needed, fix introduced in #1433