Merge branch 'suppress-allow-failure-builds' into 'master'

Suppress e-mails on failed builds if allow_failure is set

Every time I push to GitLab, I get > 2 emails saying a spec failed when I don't care about the benchmarks and others that have `allow_failure` set to `true`.

@ayufan mentioned creating a summary e-mail to prevent getting one e-mail per build, but the latter might actually be desirable. For example, I do want to know if Rubocop errors fail right away.

See merge request !2178

lib/gitlab/build_data_builder.rb

@@ -23,6 +23,7 @@ module Gitlab
           build_started_at: build.started_at,
           build_finished_at: build.finished_at,
           build_duration: build.duration,
+          build_allow_failure: build.allow_failure,
 
           # TODO: do we still need it?
           project_id: project.id,