MC-5810: Improve naming of the critical variables/parameters in the code and configuration

- Resolved incorrect less class name

Author: Hwashiang Yu

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/_panel.less

@@ -243,7 +243,7 @@
             display: block;
             width: 100%;
 
-            .this.menuSectiontitle {
+            .menu-section-title {
                 border-bottom: 1px solid @color-brownie-almost;
                 cursor: pointer;
                 padding: 9px;
@@ -283,7 +283,7 @@
             }
 
             &.active {
-                .this.menuSectiontitle {
+                .menu-section-title {
                     h4 {
                         color: @color-ivory;
                     }