fix: overlapped scrollbar in calendar

[richardshiue]

needs #3073

resolves #2618

I've removed the largest scrollbar in the calendar so that only the scrollbar in each cell will be displayed. I'd love to get some usability feedback.

Echoing my comment in #2618, since MonthView doesn't expose a scrollController, we cannot use the existing thick scrollbar as seen in the grid.

Feature Preview

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PR Checklist

• My code adheres to the AppFlowy Style Guide
• I've listed at least one issue that this PR fixes in the description above.
• I've added a test(s) to validate changes in this PR, or this PR only contains semantic changes.
• All existing tests are passing.

[codecov]

Codecov Report

Merging #3075 (5f4db3f) into main (ff79635) will decrease coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3075      +/-   ##
==========================================
- Coverage   67.89%   67.83%   -0.07%     
==========================================
  Files         443      443              
  Lines       21103    21107       +4     
==========================================
- Hits        14328    14317      -11     
- Misses       6775     6790      +15     

Flag	Coverage Δ
appflowy_flutter_integrateion_test	64.77% <100.00%> (-0.08%)	⬇️
appflowy_flutter_unit_test	12.87% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
...abase_view/calendar/presentation/calendar_day.dart	89.88% <100.00%> (+0.11%)	⬆️
...base_view/calendar/presentation/calendar_page.dart	97.08% <100.00%> (+0.04%)	⬆️

... and 4 files with indirect coverage changes