chore: Update font-sizes in QueryPreviewModal

[geido]

SUMMARY

This PR removes hacky usages of font-sizes by replacing them with the exact font-sizes available in the theme config.

BEFORE

AFTER

TESTING INSTRUCTIONS

1. Open the QueryPreview modal from the Query History or Saved Queries
2. Make sure the font-sizes look balanced

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #19620 (2f03a23) into master (761d5c4) will decrease coverage by 0.15%.
The diff coverage is 91.66%.

❗ Current head 2f03a23 differs from pull request most recent head 267aa70. Consider uploading reports for the commit 267aa70 to get more accurate results

@@            Coverage Diff             @@
##           master   #19620      +/-   ##
==========================================
- Coverage   66.68%   66.53%   -0.16%     
==========================================
  Files        1681     1681              
  Lines       64316    64319       +3     
  Branches     6565     6564       -1     
==========================================
- Hits        42888    42793      -95     
- Misses      19733    19853     +120     
+ Partials     1695     1673      -22     

Flag	Coverage Δ
javascript	51.21% <91.66%> (-0.30%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...l/AdhocFilterEditPopoverSimpleTabContent/index.tsx	65.60% <ø> (+0.52%)	⬆️
superset-frontend/src/components/Select/Select.tsx	87.28% <83.33%> (+0.36%)	⬆️
superset-frontend/src/components/Select/utils.ts	65.00% <100.00%> (+1.84%)	⬆️
...nd/src/views/CRUD/data/query/QueryPreviewModal.tsx	93.93% <100.00%> (ø)
...ws/CRUD/data/savedquery/SavedQueryPreviewModal.tsx	94.11% <100.00%> (ø)
...ts/nativeFilters/FilterBar/FilterControls/state.ts	0.00% <0.00%> (-75.00%)	⬇️
...veFilters/FilterBar/FilterControls/FilterValue.tsx	6.59% <0.00%> (-53.85%)	⬇️
...tend/src/filters/components/Time/transformProps.ts	0.00% <0.00%> (-50.00%)	⬇️
...oard/components/nativeFilters/FilterCard/index.tsx	10.00% <0.00%> (-50.00%)	⬇️
...d/src/filters/components/Time/TimeFilterPlugin.tsx	0.00% <0.00%> (-47.06%)	⬇️
... and 13 more

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[michael-s-molina]

LGTM