Optimise WikiPage spec

Locally the spec has reduced from ~45s to ~14s.

We used to spend ~35s creating 416 factories, and we now spend ~3s
creating 43 factories.

app/models/wiki.rb

@@ -106,7 +106,7 @@ class Wiki
     [WikiDirectory.group_pages(pages), limited]
   end
 
-  # Finds a page within the repository based on a tile
+  # Finds a page within the repository based on a title
   # or slug.
   #
   # title - The human readable or parameterized title of

spec/factories/wikis.rb

@@ -4,7 +4,7 @@ FactoryBot.define do
   factory :wiki do
     transient do
       container { association(:project) }
-      user { association(:user) }
+      user { container.default_owner || association(:user) }
     end
 
     initialize_with { Wiki.for_container(container, user) }