Use Half-Life Uplink maps that ship with the anniversary version of the game

[SamVanheer]

Since the anniversary update the Half-Life Uplink demo maps are included with the Steam version of the game. Change the installer to use those maps instead of requiring a separate copy. #540 covers the copying and converting of those maps, but the maps need to be tested to ensure they work as intended. Upgrades applied by the installer may need changing here.

Note that the instructions in the documentation will also need updating.

Dependencies:

• [ ] #540