UI changes for service account page for groups

What does this MR do and why?

Policy changes for service accounts be available on gitlab trial

With this policy change now groups with trial subscription will be able to create and manage service accounts

Solves - 576086 and https://gitlab.com/gitlab-org/gitlab/-/issues/573402

This MR deals with UI part as decided https://gitlab.com/gitlab-org/gitlab/-/work_items/576086#note_2813395791

With this MR -> !208997 (merged) we introduced the change where we allow service accounts to be created in system even with Groups with trial subscription, but we have an added condition for the user's identity to be verified.

Current scenario - We do not display the option Service Accounts in sidebar for Gitlab in case user is not elligible to create/delete service accounts

Change in this MR - We are showing Service accounts option in side menu for groups with trial subscription for group owner whose identity is not verified yet.

Idea is to make sure user is notified that only blocker for him/her for creating service account is that the identity is not verified yet.

Screenshots or screen recordings

Before - When user's identity is verified and group is at trial subscription

After - When user's identity is not verified and group is at trial subscription

How to set up and validate locally

Please follow the steps in this MR for setup !208997 (merged)

MR acceptance checklist

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