more lovable text colors

[ryankeairns]

Related to #199715
Closes #200160

Summary

The Kibana ES|QL + Discover teams reviewed the ES|QL editor text colors and found them to be dull relative to current theme settings. This PR makes a slight change to use base colors instead of text colors.

Note
Longer term - and this consideration was preexisting - we could explore adding a text-editor-specific set of tokens for use in Monaco editors. That said, these theme files are not React based, so this might be a challenge to handle via EUI tokens once the old javascript based theme tokens are deprecated.

Before and after

Editor in 8.X (Amsterdam theme)

Editor on main (Borealis theme)

Editor after this PR (Borealis theme)
Light mode

Dark mode

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 8f443ec

Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
kbnUiSharedDeps-srcJs	3.5MB	3.5MB	-20.0B

[ryankeairns]

Need to fix comments color in dark mode, too:

@stratoula should this be fixed separately so that it can land in 8.17.X or 8.18?

[stratoula]

Awesome Ryan, thank you so much <3

[stratoula]

Need to fix comments color in dark mode, too:

@stratoula should this be fixed separately so that it can land in 8.17.X or 8.18?

Yes is def a separate issue. Have we identified which grey looks better in dark mode?

[ryankeairns]

Need to fix comments color in dark mode, too:

@stratoula should this be fixed separately so that it can land in 8.17.X or 8.18?

Yes is def a separate issue. Have we identified which grey looks better in dark mode?

@stratoula I tried euiThemeVars.euiTextSubduedColor (change from euiTextDisabledColor) and that does the trick.
We could keep the Disabled color for light mode... or just use Subdued for both modes. Curious your personal preference when looking at this.

[stratoula]

I will check it and let you know Ryan!