Resolve "Kubernetes > Create form > Text color of error messages"

What does this MR do?

Completely uses Bootstrap 4 utility classes for error states, as text-muted uses !important.

Screenshots

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After

Does this MR meet the acceptance criteria?

• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer

What are the relevant issue numbers?

Closes #47359 (closed)