Revert "Revised text from Enterprise marketplace pop-up screen"

This reverts commit 6a334dd907eeeaf657db006a07d71618d800987f.

The commit broke the string freeze. It also hardcodes the enterprise text
for all versions of Cura (which should not be the case!)

plugins/Toolbox/resources/qml/pages/WelcomePage.qml

@@ -19,7 +19,7 @@ Column
     Label
     {
         id: welcomeTextLabel
-        text: catalog.i18nc("@description", "Please sign in to get verified plugins and materials for Ultimaker Cura Enterprise")
+        text: catalog.i18nc("@description", "Get plugins and materials verified by Ultimaker")
         width: Math.round(parent.width / 2)
         font: UM.Theme.getFont("default")
         color: UM.Theme.getColor("text")