[Linux]ノートの共有をLinuxのみ削除する

[Npepperlinux]

Related #481
Linuxの場合のみ「ノートを共有」をリストから削除するようにしました（#481 の対応1に該当）。

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 23.07692% with 10 lines in your changes missing coverage. Please review.

Project coverage is 27.60%. Comparing base (cb8696b) to head (3f8e010).
Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
lib/view/note_modal_sheet/note_modal_sheet.dart	23.07%	10 Missing ⚠️

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Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #482   +/-   ##
========================================
  Coverage    27.59%   27.60%           
========================================
  Files          312      312           
  Lines        16454    16456    +2     
========================================
+ Hits          4541     4542    +1     
- Misses       11913    11914    +1     

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