_content/solutions: fix Uber case study link and description

[mranney-dd]

The eng.uber.com domain has been retired and https://eng.uber.com/aresdb/
now returns 404 with no redirect. Two places on the site link to it:

• the Uber case study card on /solutions/
• the Uber logo in the "Companies using Go" grid on the home page
  (_content/index.md, which uses .link for entries with
  inLandingPageGrid: true)

Both currently send visitors to a dead page. This points them at the
article's current location, https://www.uber.com/blog/aresdb/, which
serves the same post ("Introducing AresDB: Uber's GPU-Powered Open Source,
Real-time Analytics Engine"). I used the locale-neutral path rather than the
/US/en/ variant that /en-US/blog/aresdb/ redirects to, to avoid pinning
the link to one locale.

Two small fixes to the same front matter while here:

• The description contained an unapplied editorial annotation,
  AresDB [,written in Go,]. _content/solutions/case-studies.md renders
  {{.description}} verbatim, so those brackets and stray commas were
  visible on the published page.
• title read "GPU-power analytics engine"; the linked article's own title
  is "GPU-Powered".

Tested with go test ./.... Two failures reproduce identically on master
and are unrelated to this change: cmd/golangorg TestAll reports a broken
link to /LICENSE, and cmd/screentest requires Google default credentials.

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[mranney-dd]

/check-cla