make Area fit within block row (#13221)

src/Umbraco.Cms.StaticAssets/wwwroot/App_Plugins/Umbraco.BlockGridEditor.DefaultCustomViews/umbBlockGridDemoImageBlock.html

@@ -19,7 +19,6 @@
         justify-content: center;
         width: 100%;
         height: 100%;
-        min-height: 100%;
         cursor: pointer;
         color: black;
         background-color: transparent;

src/Umbraco.Web.UI.Client/src/views/propertyeditors/blockgrid/blockgridui.less

@@ -279,7 +279,8 @@ ng-form.ng-invalid > .umb-block-grid__block:not(.--active) > .umb-block-grid__bl
 .umb-block-grid__block--view {
     height: 100%;
     width: 100%;
-    display: block;
+    display: flex;
+    flex-direction: column;
 }
 
 .umb-block-grid__block--context {