Remove unwanted results from wiki basic search

What does this MR do and why?

Reject the files with uploads/ and .gitlab/redirects.yml paths. These paths should not be visible in the search results.

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Before	After

How to set up and validate locally

1. Create a wiki page.
2. Upload an image with the name sample.(jpg|png|jpeg)
3. Now change the Path of the wiki to sample
4. Perform a basic search with the keyword sample.
5. You should not see results with binary content and redirects.

Related to #389375 (closed)

lib/gitlab/wiki_file_finder.rb

@@ -16,8 +16,14 @@ def search_paths(query)
       safe_query = Regexp.escape(query.tr(' ', '-'))
       safe_query = Regexp.new(safe_query, Regexp::IGNORECASE)
       paths = repository.ls_files(ref)
+      paths.reject { |path| Gitlab::UntrustedRegexp.new('^uploads\/').match?(path) }.grep(safe_query)
+    end
 
-      paths.grep(safe_query)
+    def find_by_content(query, options)
+      repository.search_files_by_content(query, ref, options).filter_map do |result|
+        blob = Gitlab::Search::FoundBlob.new(content_match: result, project: project, ref: ref, repository: repository)
+        blob unless blob.path == Wiki::REDIRECTS_YML
+      end
     end
   end
 end