Update feature flags empty state

- Align buttons in the center
- Remove double top border

ee/app/views/projects/feature_flags/_empty_state.html.haml

-.border-top
-  .row.empty-state
-    .col-12
-      .svg-content
-        = image_tag 'illustrations/feature_flag.svg'
-
-    .col-12
-      .text-content
-        %h4.text-center= s_('FeatureFlags|Get started with feature flags')
-        %p
-          = s_('FeatureFlags|Feature flags allow you to configure your code into different flavors by dynamically toggling certain functionality.')
-          = link_to 'More information', help_page_path("user/project/operations/feature_flags")
+.row.empty-state
+  .col-12
+    .svg-content
+      = image_tag 'illustrations/feature_flag.svg'
 
+  .col-12
+    .text-content
+      %h4.text-center= s_('FeatureFlags|Get started with feature flags')
+      %p
+        = s_('FeatureFlags|Feature flags allow you to configure your code into different flavors by dynamically toggling certain functionality.')
+        = link_to 'More information', help_page_path("user/project/operations/feature_flags")
+      .text-center
         = render 'new_feature_flag_button'
         = render 'configure_feature_flags_button'

ee/changelogs/unreleased/gt-update-feature-flags-empty-state.yml

+---
+title: Update feature flags empty state
+merge_request: 7967
+author: George Tsiolis
+type: other