Remove dismiss button for storage alerts that require user attention

What does this MR do and why?

As part of https://gitlab.com/gitlab-org/gitlab/-/issues/387958 we want to make the storage alerts not dismissible if the usage ratio is 95% or over.

Screenshots or screen recordings

Before	After

How to set up and validate locally

This alert has several variations. For a complete setup you can check this MR's description: !114960 (merged)

1. Create or Pick a group, take note of its ID
2. Create a project in this group, take note of its ID
3. In rails console:
   1. Gitlab::CurrentSettings.update!(repository_size_limit: 1000.megabytes)
   2. Group.find(< your group id here>).update(additional_purchased_storage_size: 100)
   3. p = Project.find(< your project id here >)
   4. p.statistics.update(repository_size: 1095.megabytes)
4. Now back to your Browser, go to: https://gdk.test:3443/groups/<your-group>/-/usage_quotas#storage-quota-tab
5. Make sure the banner has the close button on master but not on this branch.

MR acceptance checklist

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