fix(plugins/plugin-carbon-themes): optimize loading of plex fonts

[starpit]

we don't need to load every last plex font variant

Fixes #3831

Description of what you did:

My PR is a:

• 💥 Breaking change
• 🐛 Bug fix
• 💅 Enhancement
• 🚀 New feature

Please confirm that your PR fulfills these requirements

• Multiple commits are squashed into one commit.
• The commit message follows Conventional Commits, which allows us to autogenerate release notes; e.g. fix(plugins/plugin-k8s): fixed annoying bugs
• All npm dependencies are pinned.

[codecov]

Codecov Report

Merging #4312 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #4312      +/-   ##
==========================================
+ Coverage   59.44%   59.45%   +0.01%     
==========================================
  Files          74       74              
  Lines        2399     2400       +1     
  Branches      582      583       +1     
==========================================
+ Hits         1426     1427       +1     
- Misses        744      746       +2     
+ Partials      229      227       -2     

Impacted Files	Coverage Δ
packages/core/src/webapp/themes/persistence.ts	77.41% <100.00%> (+0.37%)	⬆️
packages/core/src/core/command-tree.ts	69.13% <0.00%> (-0.87%)	⬇️
packages/core/src/util/i18n.ts	64.00% <0.00%> (+8.00%)	⬆️

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