!reference tag usage with parallel:matrix keyword results in unexpected config should be an array of hashes errors

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Summary

When trying to use !reference tags for parallel:matrix, an error is displayed:

This GitLab CI configuration is invalid: jobs:build_jobs:parallel:matrix config should be an array of hashes.

Steps to reproduce

1. Add .gitlab-ci.yml with below content:

.VUE_APPS: 
  - APP_NAME: frontend
    APP_DIR: frontend
    
.DOTNET_APPS: 
  - APP_NAME: myapi1 
    APP_DIR: /apis/api1
    BASE_IMAGE: <registry_url>/aspnet6
  - APP_NAME: myapi2 
    APP_DIR: /apis/api2
    BASE_IMAGE: <registry_url>/nginx:alpine

build_jobs:
  stage: build
  parallel:
    matrix:
      - !reference [.VUE_APPS]
  script: 
    - echo "test"

2. Go to pipeline editor and it will give the error message:

This GitLab CI configuration is invalid: jobs:build_jobs:parallel:matrix config should be an array of hashes.

What is the current bug behavior?

!reference tags don't work when merging array for parallel:matrix.

What is the expected correct behavior?

Support merging parallel:matrix arrays using !reference tags.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com