fix: allow attendee multiple day checkin

[maze-runnar]

Fixes #2016
recreation of #7480

Checklist

• I have read the Contribution & Best practices Guide.
• My branch is up-to-date with the Upstream development branch.
• The acceptance, integration, unit tests and linter pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[vercel]

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[codecov]

Codecov Report

Merging #7623 (f8ea325) into development (20cd2c7) will decrease coverage by 0.07%.
The diff coverage is 5.12%.

@@               Coverage Diff               @@
##           development    #7623      +/-   ##
===============================================
- Coverage        19.82%   19.75%   -0.08%     
===============================================
  Files              602      603       +1     
  Lines             6980     7015      +35     
  Branches           149      149              
===============================================
+ Hits              1384     1386       +2     
- Misses            5569     5602      +33     
  Partials            27       27              

Impacted Files	Coverage Δ
.../controllers/events/view/tickets/attendees/list.js	0.00% <0.00%> (ø)
app/models/attendee.js	0.00% <ø> (ø)
.../cell/events/view/tickets/attendees/cell-action.js	6.66% <6.66%> (ø)

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[MeghalBisht]

@maze-runnar shouldn't these all be computed properties?

[maze-runnar]

No

[mariobehling]

The attendee checkin dropdown is unfortunately still not working, in particular when there is only one event day there is no menu choice.