Fine tune notification dot behavior

What does this MR do?

Aligns the transitions between states with the background transitions? For example before this change...

• on click, the white border of the dot shows up sooner than the background switches to white. It's the same when I click outside the menu, the border turns to blue immediately but the background first turns to the hover state and then it disappears...
• if I click the avatar again once the menu is open, the border of the dot remains white while the background returns to what I believe is hover state? Can we change the border to match that?

we are fixing the above items...

Screenshots

Before

dot__1_

After

Screen_Recording_2020-06-18_at_2.14.53_PM

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

Closes #222354