MC-3509: Image inside Text Content Type is scaled on stage

- Added styling banner, slider, and text to set image height to auto.

Author: Hwashiang Yu

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/content-type/banner/_default.less

@@ -60,6 +60,10 @@
                 position: relative;
                 top: -45px;
             }
+
+            img {
+                height: auto;
+            }
         }
 
         > .mce-edit-focus {

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/content-type/slide/_default.less

@@ -123,6 +123,10 @@
 
         [data-element='content'] {
             min-height: 50px;
+
+            img {
+                height: auto;
+            }
         }
 
         .pagebuilder-slide-button {

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/content-type/text/_default.less

@@ -33,6 +33,10 @@
             position: absolute;
             top: 5px;
         }
+
+        img {
+            height: auto;
+        }
     }
     > .mce-edit-focus {
         ~ .pagebuilder-options,