ui: Remove stray parenthesis in Jobs page

Addresses  #77440.

This commit fixes the stray parenthesis at the end of the duration time for a
succeeded job. The parenthesis had been introduced in
#76691 and the 21.2 backport
#73624.

Release note (ui): Remove stray parenthesis at the end of the duration time for
a succeeded job. It had been accidentally introduced to unreleased master and a
21.2 backport.

Release justification: Category 2, UI bug fix

pkg/ui/workspaces/db-console/src/views/jobs/duration.tsx

@@ -49,7 +49,6 @@ export class Duration extends React.PureComponent<{
         <span className={className}>
           {"Duration: " +
             formatDuration(moment.duration(finishedAt.diff(startedAt)))}
-          )
         </span>
       );
     }