Revert "Allow more htmlClasses"

This reverts commit 2b44b9e.

Author: engcom-Charlie

lib/internal/Magento/Framework/View/Layout/etc/elements.xsd

@@ -119,7 +119,7 @@
 
     <xs:simpleType name="htmlClassType">
         <xs:restriction base="xs:string">
-            <xs:pattern value="[a-zA-Z\d\-_/:.\[\]&amp;@()! ]*"/>
+            <xs:pattern value="[a-zA-Z\d\-_/:.\[\]&amp;@() ]*"/>
         </xs:restriction>
     </xs:simpleType>