feat: add max length check for email

[LashaJini]

What kind of change does this PR introduce?

feature: add max length check for email.

What is the current behavior?

Currently, email length is only checked on db side. Email has max length 255 characters, when user sends (>255 characters) large email to /admin/users endpoint, db is doing unnecessary queries.

What is the new behavior?

Code returns early if user enters large email. There will be no db queries.