chore: Hide docfx pdf command output options

[filzrev]

This PR is relating #9696.

It seems docfx pdf command's --output option is not works if manifest.json not exists at specified directory.
This PR add settings to hide option from docfx pdf --help.

Example

docfx pdf --output _site1

FileNotFoundException: Could not find file 'C:\projects\docfx\docs_site2\manifest.json'.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.00%. Comparing base (fe673ec) to head (cbf173c).
Report is 121 commits behind head on main.

❗ Current head cbf173c differs from pull request most recent head 4efe82a. Consider uploading reports for the commit 4efe82a to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9710      +/-   ##
==========================================
+ Coverage   74.31%   79.00%   +4.68%     
==========================================
  Files         536      536              
  Lines       23189    23191       +2     
  Branches     4056     4028      -28     
==========================================
+ Hits        17234    18321    +1087     
+ Misses       4853     3746    -1107     
- Partials     1102     1124      +22     

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[yufeih]

Indeed.