Use clearer error for pages when SHA is outdated

What does this MR do?

Changes the pages:deploy error message when the SHA is outdated to:

build SHA is outdated for this ref

Screenshots

Old:

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.