[PM-16858] - Desktop - Generator modal - Update submit button

[jaasen-livefront]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-16858

📔 Objective

This PR addresses the QA feedback and updates the button copy for generate passphrase modal. It also remove a legacy css class to ensure the modern button styling is applied.

📸 Screenshots

Passphrase	Password	Username

⏰ 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 – 3df7dee5-f154-4746-b5e9-7f73b99ef0a6

Great job, no security vulnerabilities found in this Pull Request

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 34.28%. Comparing base (7b11905) to head (b47948d).
Report is 74 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #12841   +/-   ##
=======================================
  Coverage   34.27%   34.28%           
=======================================
  Files        2933     2933           
  Lines       90078    90078           
  Branches    16915    16915           
=======================================
+ Hits        30877    30884    +7     
+ Misses      56743    56736    -7     
  Partials     2458     2458           

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