bug(form-field): Prefix and suffix text color mismatched from spec

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

Currently the text appears black instead of the gray color in the spec.

Reproduction

Spec: https://m2.material.io/components/text-fields
Prefix and suffix demo: https://material.angular.io/components/form-field/examples#form-field-prefix-suffix.

Expected Behavior

Text is gray

Actual Behavior

Text is black

Environment

• Angular:
• CDK/Material:
• Browser(s):
• Operating System (e.g. Windows, macOS, Ubuntu):