Explains what stage the Code Quality template job is using

What does this MR do?

This merge request adds to the documentation on the Code Quality page. It now explicitly states what stage the included Code Analysis job is using. This is my proposed fix of #33410 (closed).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

This change poses no risks, as it is a simple documentation addition.

Closes #33410 (closed)