MC-5405: Column Minimum Height Issues

- set column to grow to maximum available height instead of inheriting height
- update existing test to check expected column height

Author: anthoula

app/code/Magento/PageBuilder/Test/Mftf/Test/AdminPageBuilderColumnTest.xml

@@ -201,13 +201,9 @@
         </actionGroup>
         <actionGroup ref="validateContentTypeHeightEqualToMinHeight" stepKey="validateContentTypeHeightBeforeSave">
             <argument name="content" value="{{ColumnOnBackend.baseCSS}}"/>
-            <argument name="border" value="PageBuilderAdvancedBorderWidthProperty10"/>
-            <argument name="padding" value="PageBuilderPaddingProperty10"/>
         </actionGroup>
         <actionGroup ref="validateContentTypeHeightEqualToMinHeight" stepKey="validateContentTypeHeightAfterSave">
             <argument name="content" value="{{ColumnOnBackend.baseCSS}}"/>
-            <argument name="border" value="PageBuilderAdvancedBorderWidthProperty10"/>
-            <argument name="padding" value="PageBuilderPaddingProperty10"/>
         </actionGroup>
         <actionGroup ref="navigateToStoreFront" stepKey="navigateToStoreFront">
             <argument name="contentType" value="PageBuilderColumnContentType"/>

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

@@ -8,11 +8,11 @@
 //  _____________________________________________
 
 .pagebuilder-content-type.children-min-height.pagebuilder-column {
+    display: flex;
     margin-right: 1px;
 
     > .element-children {
-        height: 100%;
-        min-height: inherit;
+        flex: 1;
         padding: 0;
     }
 }