FEM: Change the misleading constraint descriptions regarding the geometry selection (#13921)

* FEM: Update TaskFemConstraintFixed.ui

* FEM: Update TaskFemConstraintForce.ui

* FEM: Update TaskFemConstraintTemperature.ui

* FEM: Update TaskFemConstraintDisplacement.ui

src/Mod/Fem/Gui/TaskFemConstraintDisplacement.ui

@@ -38,7 +38,7 @@
    <item>
     <widget class="QLabel" name="lbl_info">
      <property name="text">
-      <string>Select multiple face(s), click Add or Remove</string>
+      <string>Select geometric element(s), click Add or Remove</string>
      </property>
     </widget>
    </item>

src/Mod/Fem/Gui/TaskFemConstraintFixed.ui

@@ -17,7 +17,7 @@
    <item>
     <widget class="QLabel" name="lbl_info">
      <property name="text">
-      <string>Select multiple face(s), click Add or Remove</string>
+      <string>Select geometric element(s), click Add or Remove</string>
      </property>
     </widget>
    </item>

src/Mod/Fem/Gui/TaskFemConstraintForce.ui

@@ -29,7 +29,7 @@
    <item>
     <widget class="QLabel" name="lbl_info">
      <property name="text">
-      <string>Select multiple face(s), click Add or Remove</string>
+      <string>Select geometric element(s), click Add or Remove</string>
      </property>
     </widget>
    </item>

src/Mod/Fem/Gui/TaskFemConstraintTemperature.ui

@@ -17,7 +17,7 @@
    <item>
     <widget class="QLabel" name="lbl_info">
      <property name="text">
-      <string>Select multiple face(s), click Add or Remove</string>
+      <string>Select geometric element(s), click Add or Remove</string>
      </property>
     </widget>
    </item>