fix: Accessibility - change color for WCAG AA

[SphinxKnight]

Comprehensive Summary of your change

Changed the label token foreground and background to comply with WCAG AA (or AAA when possible).

Before:

After:

Using https://webaim.org/resources/contrastchecker/ as a testing tool, only label-medium was OK for WCAG AA for normal content.

Issue being fixed

No existing issue (I preferred to file a PR first). This could relate to #12327

Notes

I don't have any Sass skill so far and tried to apply a homogeneous patch where such labels were duplicated. Please let me know if I missed something.

result-tip-histogram.component.scss didn't have any issue, but I preferred to match the colors changed elsewhere.

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation" << I'm not sure I have the rights to label the PR.
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[SphinxKnight]

Thanks @Vad1mo for the swift review and sorry about the auto-merge, I just pushed to fix the reason of UI_UT CI job's failure.

[codecov]

Codecov Report

Merging #19472 (3bf7872) into main (adb066c) will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #19472      +/-   ##
==========================================
+ Coverage   67.43%   67.46%   +0.03%     
==========================================
  Files         989      989              
  Lines      108836   108836              
  Branches     2752     2752              
==========================================
+ Hits        73394    73428      +34     
+ Misses      31480    31446      -34     
  Partials     3962     3962              

Flag	Coverage Δ
unittests	67.46% <ø> (+0.03%)	⬆️

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see 7 files with indirect coverage changes

[AllForNothing]

@SphinxKnight Can you update the background color according to this #19249? The new colors this suggested by our designer.

[SphinxKnight]

@SphinxKnight Can you update the background color according to this #19249? The new colors this suggested by our designer.

Thanks for the pointer: just did in fdaab42

Edit: screenshot with the new values updated in the description. Also included here for simplicity:

[OrlinVasilev]

@SphinxKnight thank you for the PR :))

[OrlinVasilev]

@SphinxKnight congrats on merging your first PR here :)

[SphinxKnight]

@SphinxKnight congrats on merging your first PR here :)

Thanks :) eager to learn a bit more SASS to factor those tokens when time allows :)