Check minutes before displaying CI Minutes warning

What does this MR do?

Currently we display the CI Minutes warning when the last_ci_minutes_usage_notification_level is set.

This value should be cleared at times, like when purchasing more minutes. If for some reason it is not cleared, the banner will display, even though there could be minutes available.

This MR changes it so that the warning will only display if the current minutes left is still below the last notification level set on the namespace.

Displays CI Minutes warning only if minutes left is still below notification level

Screenshots

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

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

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

Closes #34947