Fix(EoA Banner): add test coverage + log error

What does this MR do?

This MR adds feature tests to the EoA banner. For more context see the comment here: !52670 (comment 498787625)

Follow-up to this MR: !52670 (merged)

Screenshots (strongly suggested)

User	Group

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

To test this out for groups

• Run the following in bin/rails c

Feature.enable(:show_billing_eoa_banner)
group = Group.find_by_full_path('h5bp')
subscription = GitlabSubscription.where(namespace_id: group.id)[0]
subscription.update(hosted_plan_id: 1)
current_user = User.find_by(username: 'root')
group.add_owner(current_user.id)

• Navigate to http://localhost:3000/groups/h5bp/-/billings
• You should see the banner

To test this out for users

• Run the following in bin/rails c

Feature.enable(:show_billing_eoa_banner)
current_user = User.find_by(username: 'root')
subscription = GitlabSubscription.where(namespace_id: current_user.namespace.id)[0]
subscription.update(hosted_plan_id: 1)

• Navigate to http://localhost:3000/-/profile/billings
• You should see the banner

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related to #271523