Fix activity feed dashboard link

[pmbrull]

Activity feed from Metabase creates the link properly as /dashboard/...

In Looker we are creating it as /table/...

[aniketkatkar97]

As of now, we don't have a page dedicated to showing chart details, there won't be a proper link to redirect the user.
We will handle this issue later as we are thinking about adding the chart details page.

[Ashish8689]

@mohityadav766 @harshach

For the dashboard chart entity feed, we are not getting the correct entity link, for example, we have dashboard sample_looker.customers and it has charts chart_1 and chart_2. so if we make any changes to chart_1, the change event is generated, however, the about attribute has the wrong entity link.

It has <E::chart::sample_looker.chart_1>, instead of <E::chart::sample_looker.customers.chart_1>