Remove unused skipped CSS rule

What does this MR do and why?

Remove unused skipped CSS rule that is overridden in the same file:

ci-skipped is present twice, so only the last CSS rule gets applied.

Screenshots or screen recordings

How to set up and validate locally

Run a pipeline that fails in its first stage while skip the next jobs:

stages:
  - fail
  - build

fail-job:
  stage: fail
  script:
    - exit 1

build-job: # will get skipped
  stage: build
  script:
    - echo "Compiling the code..."
    - echo "Compile complete."

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #389420