Redis: switch encoding method for password in URI

Summary

Switch from URI.escape to ERB::Util::url_encode for Redis password within the generated URI.

Closes #1701 (closed)

Note: for testing, a manually created secret with + in the password is required. This is read during container execution, and not testable via RSpec.

Testing

redis-password: something+bad'too

Before

git@i1701-webservice-6bc5d7b5f6-k7gdq:/$ cat /srv/gitlab/config/resque.yml
production:
  url: redis://:something+bad%27too@i1701-redis-master:6379

After

git@i1701-webservice-6bc5d7b5f6-k7gdq:/$ cat /srv/gitlab/config/resque.yml
production:
  url: redis://:something%2Bbad%27too@i1701-redis-master:6379