[Login] Improve login flow for accounts with suspicious emails

[hichamboushaba]

Use Magic Login for accounts that use suspicious emails (unverified) instead of asking them to sign in using their usernames:
pe5sF9-3H5-p2

[dangermattic]

🚫 Please add a type label (e.g. type: enhancement) and a feature label (e.g. feature: stats) to this issue.