[SES-1956] Attachment download job re-start preventer removed

[AL-Session]

Contributor checklist

• [X] I am following the Code Style Guidelines
• [X] I have tested my contribution on these devices:
  • Virtual Pixel 3a Android 14 / API 34
• [X] My contribution is fully baked and ready to be merged as is
• [X] I ensure that all the open issues my contribution fixes are mentioned in the commit message of my first commit using the Fixes #1234 syntax

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Description

Remove list-based mechanism that attempted to prevent failed attachment download jobs from restarting.