Polish the instance overview cards

What does this MR do and why?

The admin dashboard overview is the main landing page for Administrators. The Instance overview has been untouched for years and needed some UI polish 🧡

This change namely does three functional things:

1. Combines the [ projects/users/groups ] stat cards with the list cards sitting farther below. This ties the content together
2. Removes a decent number of ? links. Often these would point to documentation for configuration, so instead they are presented if there is not a direct link to adjust the configuration of the feature.
3. Move the direct links to settings pages to a configure button

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Open the Admin Area
2. Check the links and various cards

app/assets/javascripts/admin/statistics_panel/components/app.vue

@@ -28,8 +28,12 @@ export default {
 </script>
 
 <template>
-  <gl-card class="gl-h-full" footer-class="gl-h-full">
-    <h3 class="gl-m-0 gl-self-center gl-text-base">{{ __('Statistics') }}</h3>
+  <gl-card class="gl-h-full" footer-class="gl-h-full gl-py-0">
+    <template #default>
+      <h3 class="gl-m-0 gl-inline-flex gl-items-center gl-gap-2 gl-self-center gl-text-base">
+        {{ __('Statistics') }}
+      </h3>
+    </template>
     <template #footer>
       <gl-loading-icon v-if="isLoading" size="md" class="my-3" />
       <template v-else>
@@ -41,7 +45,6 @@ export default {
             'gl-py-4',
             'gl-m-0',
             { 'gl-border-b': index !== getStatistics(statisticsLabels).length - 1 },
-            { 'gl-pt-0': index === 0 },
           ]"
         >
           {{ statistic.label }}