Fix insights notice text with YAML anchors

What does this MR do?

This MR fixes the notice text on the insights page when there are filtered out charts/items.

Bug:

When the insights YAML file contains anchors, the #notice_text method wrongfully detects "difference" in the config (items filtered out).

Example:

projectsOnly: &projectsOnly # anchor, should be ignored when comparing original and filtered out config
  projects:
    only:
      - 4359271
page1: # valid page configuration
  title: hi
  charts:
    ...
page2: # valid page configuratiuon
  title: hi
  charts:
    ...

Expected:

• Do not show the notice text.

Current:

• It shows the notice text because the original config differs from the filtered out config.

Resources

• Our insights config with anchor: https://gitlab.com/gitlab-org/quality/insights-config/-/blob/master/.gitlab/insights.yml
• The gitlab project is configured for all pages, there shouldn't be any notice text: https://gitlab.com/gitlab-org/gitlab/insights

  Some items are not visible beacuse the project was filtered out in the insights.yml file (see the projects.only config for more information).

• Valid notice text, since the project is mostly filtered out with projects.only: https://gitlab.com/gitlab-org/uxr_insights/insights/
• Previous MR: !30988 (merged)
• Original issue: #212688 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team