Restructure SSH key table partial rendering

Prior, we were double-checking `@keys.any?`, and unnecessarily assigning
`is_admin` in a view where it wasn't needed.

app/views/profiles/keys/_key_table.html.haml

-- is_admin = defined?(admin) ? true : false
+- is_admin = local_assigns.fetch(:admin, false)
+
 - if @keys.any?
   %ul.well-list
-    - @keys.each do |key|
-      = render 'profiles/keys/key', key: key, is_admin: is_admin
+    = render partial: 'profiles/keys/key', collection: @keys, locals: { is_admin: is_admin }
+- else
+  %p.profile-settings-message.text-center
+    - if is_admin
+      There are no SSH keys associated with this account.
+    - else
+      There are no SSH keys with access to your account.

app/views/profiles/keys/index.html.haml

 - page_title "SSH Keys"
 - header_title page_title, profile_keys_path
-- is_admin = defined?(admin) ? true : false
 
 .row.prepend-top-default
   .col-lg-3.profile-settings-sidebar
@@ -19,11 +18,4 @@
     %h5
       Your SSH keys (#{@keys.count})
     %div.append-bottom-default
-      - if @keys.any?
       = render 'key_table'
-      - else
-        %p.profile-settings-message.text-center
-          - if is_admin
-            User has no ssh keys
-          - else
-            There are no SSH keys with access to your account.