Include local project CI in Compliance CI template

What does this MR do?

This MR ensures the local Project CI template is always included in the Compliance CI template.

This MR addresses an issue described below:

Steps to reproduce

1. Create a Compliance CI template in the Compliance project

compliance_job:
  stage: build
  script:
    - echo "Performing compliance build steps"

2. Create a Compliance framework (e.g SOX) and associate with the Compliance CI template
3. Assign the Compliance framework to a Developer project
4. Given the following CI template existed on the default branch on the Developer project

test_job:
  stage: test
  script:
    - echo "Performing test steps"

5. Create an MR that modifies the .gitlab-ci.yml file in the Developer project.

test_job:
  stage: test
  script:
    - echo "Performing test steps"
+
+ new_job:
+   stage: test
+   script:
+     - echo "Performing new steps"

6. Observe that the pipeline in the MR uses the Compliance CI template .gitlab-ci.yml file defined in the default branch's .gitlab-ci.yml and ignores any changes made in the MR.

Before

compliance_job:
  stage: build
  script:
    - echo "Performing compliance build steps"

test_job:
  stage: test
  script:
    - echo "Performing test steps"

After

compliance_job:
  stage: build
  script:
    - echo "Performing compliance build steps"

test_job:
  stage: test
  script:
    - echo "Performing test steps"

new_job:
  stage: test
  script:
    - echo "Performing new steps"

Does this MR meet the acceptance criteria?

Conformity

• I have included a changelog entry, or it's not needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Related to #331506 (closed)