[stable4.7] fix: always show alarm unit in pural

[backportbot]

Backport of PR #6752

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 15.51%. Comparing base (b16371c) to head (6fc731a).
Report is 3 commits behind head on stable4.7.

Files with missing lines	Patch %	Lines
...rc/components/Editor/Alarm/AlarmTimeUnitSelect.vue	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           stable4.7    #6756   +/-   ##
==========================================
  Coverage      15.51%   15.51%           
==========================================
  Files            206      206           
  Lines           9258     9258           
  Branches        1932     1932           
==========================================
  Hits            1436     1436           
  Misses          7822     7822           

Flag	Coverage Δ
javascript	15.51% <0.00%> (ø)

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