fix: Sidebar renders above the lightbox layer

[miya]

Task

#139734 [v7][design] 画像プレビューがサイドバーに隠れてしまう問題の修正 ┗ #140638 修正

[reg-suit[bot]]

reg-suit detected visual differences.

Check this report, and review them.

:red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle::red_circle: :white_circle: :black_circle: :large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle::large_blue_circle:

What do the circles mean?

The number of circles represent the number of changed images.
:red_circle: : Changed items, :white_circle: : New items, :black_circle: : Deleted items, and :large_blue_circle: Passed items

How can I change the check status?

If reviewers approve this PR, the reg context status will be green automatically.

[yuki-takei]

https://github.com/weseek/growi/pull/8673 で解決したのでこの PR は reject します