Rename DevOps Score in the product to DevOps Report

What does this MR do?

This MR renames DevOps Score to DevOps Report. Specifically the following changes are introduced:

1. Update documentation to rename DevOps Score to DevOps Report
2. In the product, where the phrase DevOps Score is, rename it to DevOps Report
3. In the product, where the phrase Index Score is, rename it to DevOps Score

Note: To keep the changes in this MR small, references, variables and routes have not been changed. There's a follow-up issue in #241698 (closed) to clean up the codebase.

Screenshots

N/A

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

Contributes #235820 (closed)