ui: Fix nspace spacing issue (#10157)

This fixes the spacing bug in nspaces only by only showing Description if the namespace has one, and removing the extra 2 pixel margin of dds for when dts aren't rendered/don't exist.

.changelog/10157.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+ui: Don't render a DOM element for empty namespace descriptions
+```

ui/packages/consul-ui/app/components/consul/nspace/list/index.hbs

@@ -14,12 +14,14 @@ as |item|>
 {{/if}}
     </BlockSlot>
     <BlockSlot @name="details">
+{{#if item.Description}}
       <dl>
         <dt>Description</dt>
         <dd data-test-description>
           {{item.Description}}
         </dd>
       </dl>
+{{/if}}
   {{#if (env 'CONSUL_ACLS_ENABLED')}}
       <Consul::Token::Ruleset::List @item={{item}} />
   {{/if}}

ui/packages/consul-ui/app/styles/components/composite-row.scss

@@ -16,14 +16,20 @@
 .consul-lock-session-list ul > li:not(:first-child) {
   @extend %with-one-action-row;
 }
-// TODO: This hides the icons-less dt's in the below lists as they don't have
+// TODO: This hides the iconless dt's in the below lists as they don't have
 // tooltips the todo would be to wrap these texts in spans
 .consul-nspace-list > ul > li:not(:first-child) dt,
 .consul-token-list > ul > li:not(:first-child) dt,
 .consul-policy-list > ul li:not(:first-child) dl:not(.datacenter) dt,
 .consul-role-list > ul > li:not(:first-child) dt {
+  @extend %iconless-dt;
+}
+%iconless-dt {
   display: none;
 }
+%iconless-dt + dd {
+  margin-left: 0 !important;
+}
 /* TODO: the service list has a 1px offset */
 .consul-policy-list dl.datacenter dt,
 .consul-service-list li > div:first-child > dl:first-child dd {