Upgrade to Ruby 2.4.4

Fixes that make this work:

• A change in Ruby (https://github.com/ruby/ruby/commit/ce635262f53b760284d56bb1027baebaaec175d1) requires passing in the exact required length for OpenSSL keys and IVs.

• Ensure the secrets.yml is generated before any prepended modules are loaded. This is done by renaming the secret_token.rb initializer to 01_secret_token.rb, which is a bit ugly but involves the least impact on other files.

Relates to Omnibus issue: omnibus-gitlab#2588 (closed)

Related MRs:

• Gitaly MR: gitaly!725 (merged)
• EE port: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5783
• GDK: gitlab-development-kit!471 (merged)

Other notes:

It's possible other lingering bugs are out there (e.g. see https://gitlab.com/gitlab-org/gitlab-ce/issues/35769#note_36342006 as something that's a bit unexpected).

See: omnibus-gitlab#2588 (closed)