Removed eu-environment feature flag

[trmartin4]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-8817

📔 Objective

Remove the eu-environment feature flag from the server, since all clients are no longer referencing it.

This was originally reverted with #4177 in order to allow the mobile apps to remove the reference. With the 2024.10.0 releases we've had this flag out of the code for long enough for backward compatibility.

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Protected functional changes with optionality (feature flags)
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation (Confluence, contributing docs) or informed the documentation team

🦮 Reviewer guidelines

• 👍 (:+1:) or similar for great changes
• 📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
• ❓ (:question:) for questions
• 🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed issue and could potentially benefit from discussion
• 🎨 (:art:) for suggestions / improvements
• ❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
• 🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
• ⛏ (:pick:) for minor or nitpick changes

[github-actions]

LaunchDarkly flag references

❌ 1 flag removed

Name	Key	Aliases found	Info
Display EU Environment	display-eu-environment		✅ all references removed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.57%. Comparing base (edd31bc) to head (ba16efb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4966   +/-   ##
=======================================
  Coverage   42.57%   42.57%           
=======================================
  Files        1387     1387           
  Lines       64653    64653           
  Branches     5933     5933           
=======================================
  Hits        27528    27528           
  Misses      35903    35903           
  Partials     1222     1222           

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[ike-kottlowski]

There is a reference to this feature flag in the IOS codebase. It is not used; it is only referenced in a JSON configuration file as an option.

This change should have no effect on the function of the mobile clients.