[Gui] revert setting unit factor for F/m

- see https://github.com/FreeCAD/FreeCAD/commit/9db5dff7#r81159352

src/Base/UnitsSchemaInternal.cpp

@@ -435,10 +435,6 @@ QString UnitsSchemaInternal::schemaTranslate(const Quantity &quant, double &fact
             factor = 1e6;
         }
     }
-    else if (unit == Unit::VacuumPermittivity) {
-        unitString = QString::fromLatin1("F/m");
-        factor = 1;
-    }
     else if (unit == Unit::Frequency) {
         if (UnitValue < 1e3) {
             unitString = QString::fromLatin1("Hz");

src/Base/UnitsSchemaMKS.cpp

@@ -383,10 +383,6 @@ QString UnitsSchemaMKS::schemaTranslate(const Quantity &quant, double &factor, Q
             factor = 1e6;
         }
     }
-    else if (unit == Unit::VacuumPermittivity) {
-            unitString = QString::fromLatin1("F/m");
-            factor = 1;
-    }
     else if (unit == Unit::Work) {
         if (UnitValue < 1.602176634e-10) {
             unitString = QString::fromLatin1("eV");