Replace "Newly translated strings found" with "Changes in translated strings found" in gl pipeline

What does this MR do?

When removing code we are also likely to find messages removed in gettext.

Our current message states Newly translated strings found is not always true, if we have removed code.

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