PEAR::SOAP は PHP8 で動作しないため削除

[nanasess]

refs #355

• 元々 EC-CUBE本体では使用しておらず、一部の決済モジュール向けにバンドルしていたが、PHP8 の環境では動作しないため削除
• SOAP が必要な場合は SOAP extension を使用する

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.94%. Comparing base (980ce37) to head (0b479a7).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1092   +/-   ##
=======================================
  Coverage   50.94%   50.94%           
=======================================
  Files          80       80           
  Lines       10256    10256           
=======================================
  Hits         5225     5225           
  Misses       5031     5031           

Flag	Coverage Δ
tests	50.94% <ø> (ø)

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