Do not set PF side density

Let PF itself set it to the smallest possible value.

GameData/RP-1/Tree/PFTechLevels.cfg

@@ -75,7 +75,6 @@ PARTUPGRADE
 	{
 		!_applyPFMassUpgrades = DEL
 
-		%density = 0.18
 		%minDensity = 0.18
 		%maxDensity = 1.0
 		%stepDensity = 0.001
@@ -85,42 +84,36 @@ PARTUPGRADE
 			{
 				name__ = PFTech-Fairing-I
 				description__ = You can now use 1950s Aluminum stringer-stiffened fairings and stringers.
-				density = 0.155
 				minDensity = 0.155
 			}
 			UPGRADE
 			{
 				name__ = PFTech-Fairing-II
 				description__ = You can now use 1960s Magnesium stringer-stiffened fairings and stringers.
-				density = 0.143
 				minDensity = 0.143
 			}
 			UPGRADE
 			{
 				name__ = PFTech-Fairing-III
 				description__ = You can now use late 1960s Fiberglass stringer-stiffened fairings and stringers.
-				density = 0.074
 				minDensity = 0.074
 			}
 			UPGRADE
 			{
 				name__ = PFTech-Fairing-IV
 				description__ = You can now use 1980s Aluminum isogrid fairings and stringers.
-				density = 0.068
 				minDensity = 0.068
 			}
 			UPGRADE
 			{
 				name__ = PFTech-Fairing-V
 				description__ = You can now use 1990s composite monocoque fairings and stringers.
-				density = 0.042
 				minDensity = 0.042
 			}
 			UPGRADE
 			{
 				name__ = PFTech-Fairing-VI
 				description__ = You can now use 2010s advanced composite monocoque fairings and stringers.
-				density = 0.04
 				minDensity = 0.04
 			}
 		}