Before the dimensions on the Metrics tab were hardcoded,
now they are read from the URL and are filtered based on
the 'dim_' prefix.
Furthermore, modified the URL for the Graph Metrics button
to append dim_ prefix for dimensions.
Change-Id: I5f71b17ffba48f2cfbad9d299285b6deb9dccd6f
Story: 2001179
Task: 4914