MAGETWO-92697: Add vertical alignment to column configuration

- stabilize test: fix column padding and row height

Author: anthoula

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

@@ -45,8 +45,8 @@
             <argument name="contentType" value="PageBuilderColumnContentType"/>
             <argument name="index" value="1"/>
             <argument name="containerDefaultHeight" value="PageBuilderEmptyColumnHeightProperty"/>
-            <argument name="expectedPaddingTop" value="PageBuilderAdvancedMarginsAndPaddingPropertyDefault"/>
-            <argument name="expectedPaddingBottom" value="PageBuilderAdvancedMarginsAndPaddingPropertyDefault"/>
+            <argument name="expectedPaddingTop" value="PageBuilderPaddingProperty10"/>
+            <argument name="expectedPaddingBottom" value="PageBuilderPaddingProperty10"/>
         </actionGroup>
         <executeJS function="{{PageBuilderActionsSection.computedHeightOnStage(PageBuilderColumnContentType.role,'1')}}" stepKey="actualStageInitialColumnHeight"/>
         <comment userInput="Validate Row Height adjusts to Column Height" stepKey="commentValidateRowHeightAdjustToColumn"/>

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

@@ -41,5 +41,9 @@
 
     &.empty-container {
         min-height: 300px;
+
+        > .element-children {
+            margin-bottom: 1px;
+        }
     }
 }