Stop leaking Grape::Endpoint mocks for GitHub and BitBucket

spec/requests/api/import_bitbucket_server_spec.rb

@@ -198,6 +198,10 @@ RSpec.describe API::ImportBitbucketServer do
         end
       end
 
+      after do
+        Grape::Endpoint.before_each nil
+      end
+
       it 'raises a connection error' do
         post api("/import/bitbucket_server", user), params: {
           bitbucket_server_url: base_uri,

spec/requests/api/import_github_spec.rb

@@ -26,6 +26,10 @@ RSpec.describe API::ImportGithub do
       end
     end
 
+    after do
+      Grape::Endpoint.before_each nil
+    end
+
     it 'rejects requests when Github Importer is disabled' do
       stub_application_setting(import_sources: nil)