Remove Redundant User Blocking in EE Registrations Controller

What does this MR do and why?

Remove redundant user blocking in EE::RegistrationsController.

This same check of the user cap setting is also made in the EE::Users::BuildService with the same result of setting the user state to blocked pending approval.

Issue: #361563

MR acceptance checklist

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Screen recordings

In all the below recordings, there is an instance wide user cap that has been exceeded. So the new user is blocked pending admin approval.

Behavior both before and after this change is the same.

New User Signs Up

Before	After
NewUserSignupBefore	NewUserSignupAfterDeleteCode

Inviting a New User

Before	After
InviteGuestBefore	InviteGuestAfterDeleteCode