Fix Video Scrubber focus styles

[jeferson-sb]

What does this PR do?

Change video scrubber (progress bar) focus indicator styles to match existing grommet styles.

Where should the reviewer start?

src/js/components/Video/StyledVideo.js

What testing has been done on this PR?

yarn test

How should this be manually tested?

Do Jest tests follow these best practices?

• screen is used for querying.
• The correct query is used. (Refer to this list of queries)
• userEvent is used in place of fireEvent.
• asFragment() is used for snapshot testing.

Any background context you want to provide?

What are the relevant issues?

Relevant to #6170

Screenshots (if appropriate)

Do the grommet docs need to be updated?

No

Should this PR be mentioned in the release notes?

Is this change backwards compatible or is it a breaking change?

backwards compatible

[jcfilben]

Just need to update the snapshots (run yarn test -u) and then this should be good to go

[jcfilben]

Looks good!