Fix calls to registering from email query

What does this MR do and why?

Fix calls to registering from email query

• allow invites to start onboarding
• fix invite detection

How to set up and validate locally

No changes, running the invite specs in spec/features/invites_spec.rb and ee/spec/features/registrations/saas/invite_flow_spec.rb verify this fix.

Some are quarantined so need to be ran like this:

bundle exec rspec spec/features/invites_spec.rb
bundle exec rspec spec/features/invites_spec.rb --tag quarantine
bundle exec rspec ee/spec/features/registrations/saas/invite_flow_spec.rb
bundle exec rspec ee/spec/features/registrations/saas/invite_flow_spec.rb --tag quarantine

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.

Related to #411858 (closed)