Alter the GHSL built up ratio for osm incomplete tiles buy adding a multiplier to the built area assesment view

When it comes to tiles that have a high or complete coverage of GHSL built area and a low built area of real building footprints, the built up area ratio is quite low, and lower than the 0.25 threshold set as a rule to call a tile complete. In these cases there is a large overestimation of the number of buildings. It would be better to use the same factor used to set a tile as complete (0.25) to lower the GHSL built area instead of treating it as equal to that of building footprints.