Fixes #36819 - Bump sidekiq to at least 6.5

Fixes #35414 - Drop sd_notify usage

Sidekiq should be doing this on its own behind the scenes

Fixes #35414 - Bump Sidekiq to 6.3.z

As a side effect, gitlab-sidekiq-fetcher should get updated to >= 7.1.0.

Currently latest sidekiq is 6.5.5, but anything above 6.4.0 is rather
verbose about things being deprecated in sidekiq 7.0.0.

Similarly, latest redis is 4.8.0, but anything above 4.5.0 is rather...

Fixes #30730 - Implement systemd notify support for dynflow-sidekiq

Refs #28064 - add sidekiq configs