Fix removal of border from account listing (#31432)

app/javascript/styles/mastodon/admin.scss

@@ -872,6 +872,7 @@ a.name-tag,
 
     .account {
       padding: 0;
+      border: none;
 
       &__avatar-wrapper {
         margin-inline-start: 0;

app/javascript/styles/mastodon/components.scss

@@ -1808,6 +1808,7 @@ body > [data-popper-placement] {
 
 .account {
   padding: 16px;
+  border-bottom: 1px solid var(--background-border-color);
 
   .account__display-name {
     flex: 1 1 auto;