MySQL8 利用インストール時に既存テーブルの削除ができないのを修正

[nanasess]

• MySQL8 利用インストール時に既存テーブルが存在するとホワイトスクリーンになっていたのを解消
• drop_table.sql に存在しないテーブルが入っていたのを削除
• eccube_install.sh の Web版インストーラには存在しないシーケンスを削除
• refs バージョンの更新(PHP8.4-rc → PHP8.4, Ubuntu-22.04 → Ubuntu-24.04) #1072

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 51.67%. Comparing base (7b11307) to head (1e36059).
Report is 22 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1079   +/-   ##
=======================================
  Coverage   51.67%   51.67%           
=======================================
  Files          80       80           
  Lines       10224    10224           
=======================================
  Hits         5283     5283           
  Misses       4941     4941           

Flag	Coverage Δ
tests	51.67% <ø> (ø)

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