[Bug]: Theme Designer - Default text colours (neutral foregrounds & black) are incorrect

Library

React / v8 (@fluentui/react)

System Info

On site: https://fluentuipr.z22.web.core.windows.net/heads/master/theming-designer/index.html

Are you reporting Accessibility issue?

yes

Reproduction

https://fluentuipr.z22.web.core.windows.net/heads/master/theming-designer/index.html

Bug Description

This is the same as #10958 and the fix in that issue is not actively working and theme generator produces non-ally compliant results.

Video:

https://github.com/microsoft/fluentui/assets/2684369/2b45bbb5-713f-4007-8345-50f537d063b1

Actual Behavior

Replace the default text color in the theme generator with the same value. The result is different to the default and not ally compliant.

Expected Behavior

Theme generator should produce the same, a11y compliant, result as the defaults when the site first loads.

Logs

No response

Requested priority

High

Products/sites affected

No response

Are you willing to submit a PR to fix?

yes

Validations

• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• The provided reproduction is a minimal reproducible example of the bug.

Start with the linked Theme Designer reproduction and compare the default text colours with the result after replacing each value with the same value. Trace the Theme Designer's theme-generation entry point and the prior fix in issue #10958; done means unchanged values produce the same default colours and the generated theme is accessibility compliant.