Gitlab::Auth: Replace misused term with IpBlocked

What does this MR do and why?

This MR replaces a misused term with Gitlab::Auth::IpBlocked.

RuboCop's TODO list for Naming/InclusiveLanguage was regenerated via rake rubocop:todo:generate[Naming/InclusiveLanguage]. The "grace period" was removed.

Found while working on !114787 (merged).

How to set up and validate locally

bundle exec rubocop --only Naming/InclusiveLanguage

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.