clones req with the right mode before to insert or update

[ValJed]

PRO-5624

Summary

When importing draft documents they had corrupted data because req.mode needs to match doc.aposMode otherwise the core beforeInsert does weird stuff reassigning only aposMode of the document based on req.mode.

What are the specific steps to test this change?

When importing you never end up with data like that:

    _id: 'cltx1oo3m000lqvmd6yy1cwnw:en:draft',
    title: 'test',
    aposLocale: 'en:draft',
    aposMode: 'published',

What kind of change does this PR introduce?

• Bug fix
• New feature
• Refactor
• Documentation
• Build-related changes
• Other

Make sure the PR fulfills these requirements:

• It includes a) the existing issue ID being resolved, b) a convincing reason for adding this feature, or c) a clear description of the bug it resolves
• The changelog is updated
• Related documentation has been updated
• Related tests have been updated

[linear]

PRO-5624 Bug related to importing a piece or a page