Fixed issue with activity links not being consistent

## What does this MR do?

Previously, links for opening an issue/merge request & commenting where different. Opening would only have a link on the number whereas commenting would have link on the text as well. This standardises it to include the type as well (ie. issue)

## What are the relevant issue numbers?

Closes #17621 

## Screenshots (if relevant)

![Screen_Shot_2016-06-01_at_12.12.09](/uploads/c778b007e6b6c068fcae30e34409ce98/Screen_Shot_2016-06-01_at_12.12.09.png)

See merge request !4400