Feedback on migration_portal 5 - "ALTER SYSTEM SET UNDO_RETENTION = 2400;"

### Summary

undo_retention is a setting in time unit, not size.

### Where did you see the problem?

https://github.com/EnterpriseDB/docs/blob/6377ace43b3ab72d17e361749f368200a4def72c/product_docs/docs/migration_portal/5/known_issues_notes.mdx


### Expected behavior

_No response_

### Screenshots

_No response_

### Browser / Platform

_No response_

### Additional notes

_No response_