[CL-317][CL-502] Remove Storybook combined Light + Dark theme, Nord theme, and Solarized theme

[vleague2]

🎟️ Tracking

CL-317
CL-502

📔 Objective

This PR removes the combined light and dark mode theme from Storybook. It was causing some issues (stories using routers had issues; we've seen some snapshot flakiness that may be related to rendering both themes; etc), so we are moving towards viewing the themes separately. This means Chromatic will only capture snapshots in light theme.

This PR also moves the theme class location to the body, which fixes an issue where some elements (dialogs, popups, menus, etc) that are body-appended were not rendering in the correct theme.

This PR also removes the Nord and Solarized themes from Storybook. These are in the process of being deprecated from the clients, so we don't need to document them / encourage their use in Storybook.

📸 Screenshots

Before:

before.2.mov

After:

after.2.mov

⏰ 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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 35.29%. Comparing base (a038371) to head (6d48b37).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13360      +/-   ##
==========================================
+ Coverage   35.20%   35.29%   +0.08%     
==========================================
  Files        3127     3124       -3     
  Lines       92568    92345     -223     
  Branches    16857    16791      -66     
==========================================
+ Hits        32590    32593       +3     
+ Misses      57521    57295     -226     
  Partials     2457     2457              

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[github-actions]

Checkmarx One – Scan Summary & Details – ee7f845e-a6b5-4c3d-922f-d64149c67b29

Great job, no security vulnerabilities found in this Pull Request