Regression: Fix migration 125 checking for settings field

[sampaiodiego]

Closes #11353

Unfortunate seems like some databases have settings field on users as null, which causes migration 125 to fail.

This will fix the migration for those who have not ran it yet.

For those who are still locked on migration 125, upgrading to a new release with this fix will require the migration to be unlocked manually only using the following command:

db.migrations.update({ version: 124, locked: true }, { $set: { version: 124, locked: false } })

For those who have skipped migration 125-129 manually, the recommended action is to revert back to version 125 and start the server with this fix. To revert back you can use the following command:

db.migrations.update({ version: 129, locked: false }, { $set: { version: 124 } })

And finally for those still stuck with the migration locked, just updating to latest version/codebase will fix it.