Dismiss user notification dot upon acknowledgement

What does this MR do?

Acknowledge user notification dot once the user clicks on the Buy Pipeline minutes link.

Never show again. We'll follow up on improving the ability to show this notification dot to a user again in follow up UI issues.

Note: The notification dot is behind an experiment/feature flag, so there is no changelog.

Screenshots

User acknowledges by clicking on the link, then when revisit the same page, only the Buy Pipeline minutes link exists with subtext and notification dot is gone.

Screen_Recording_2020-06-19_at_11.12.29_AM

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
• 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

Contributes to #221063