Remove redundant inside gov links

https://www.gov.uk/search?q=how+government+works currently returns two copies of the result "How government works". 

This is because Whitehall puts a link into the ``government`` index for this page as well. This wasn't a problem until we displayed the top 3 results above the tabs.

The fact that this link was in this repo twice is coincidental.

Also removes some other duplication.