Use proper attached properties for Kirigami colorset

PC3 tooltips are using the incorrect attached property to define the used color set, so using third-party Plasma styles can lead to unreadable tooltips. This is probably an oversight from Plasma 5.

Before:

After:

Example color sets for Tooltip and Window, where despite ForegroundNormal being black, the text appears white as a result of mistakenly pulling the color set from Colors:Window

[Colors:Tooltip]
BackgroundAlternate=10,10,10
BackgroundNormal=242,242,247
DecorationFocus=30,146,255
DecorationHover=25,182,238
ForegroundActive=245,121,0
ForegroundInactive=175,176,179
ForegroundLink=25,182,238
ForegroundNegative=223,56,44
ForegroundNeutral=233,194,19
ForegroundNormal=0,0,0
ForegroundPositive=50,205,50
ForegroundVisited=25,182,238

[Colors:Window]
BackgroundAlternate=10,10,10
BackgroundNormal=62,69,85
DecorationFocus=30,146,255
DecorationHover=25,182,238
ForegroundActive=245,121,0
ForegroundInactive=175,176,179
ForegroundLink=0,251,255
ForegroundNegative=223,56,44
ForegroundNeutral=233,194,19
ForegroundNormal=255,255,255
ForegroundPositive=50,205,50
ForegroundVisited=25,182,238