Revert "Merge branch 'litvinov.evgeny/7314-backup-files-skip-warning' into 'master'"

What does this MR do?

From !40572 (comment 410422915): The backup can still fail due to the tar exit code of 1 regardless of suppressing the "file changed" warnings.

Therefore this MR reverts the suppression of file changed warnings, since it does not fix the bug.

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.