Remove `scim_token_vue` feature flag

What does this MR do and why?

Related to #347270 (closed)

Removes the scim_token_vue feature flag. Feature flag has been enabled for all of %14.7 without issues so it is time to remove it.

Screenshots or screen recordings

For context

Before (with feature flag disabled)

Screen_Recording_2021-12-06_at_3.53.21_PM

After

Untitled__5_

How to set up and validate locally

1. Setup SAML using the GDK guide: https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/saml.md#gitlab-configuration
   • For this SAML feature the only section you need to complete is the GitLab configuration section
2. Navigate to a group -> Settings -> SAML SSO
3. Click Generate a SCIM token

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.