[PM-28300] Remove BlockClaimedDomainAccountCreation feature flag checks

[r-tome]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-28300

📔 Objective

Remove feature flag checks for BlockClaimedDomainAccountCreation.

Clients PR.

⏰ 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]

Checkmarx One – Scan Summary & Details – bc5d2bae-f3a8-42dd-a6c9-3d3877325c6b

Great job! No new security vulnerabilities introduced in this pull request

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.08%. Comparing base (51aa419) to head (572d610).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6934      +/-   ##
==========================================
- Coverage   60.01%   56.08%   -3.93%     
==========================================
  Files        1971     1971              
  Lines       87090    87077      -13     
  Branches     7759     7756       -3     
==========================================
- Hits        52266    48840    -3426     
- Misses      32928    36428    +3500     
+ Partials     1896     1809      -87     

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[Patrick-Pimentel-Bitwarden]

👍 Auth changes look good!