When jaeger is disabled we still add GITLAB_TRACING env variables
Overview
We are still setting GITLAB_TRACING env variables even when jaeger is disabled.
This led to rails-background-jobs
(sidekiq) and rails-web
(puma) to spam this kind of log messages:
Failure while sending a batch of spans: Failed to open TCP connection to localhost:14268 (Connection refused - connect(2) for "localhost" port 14268)
Proposal (optional)
When jaeger is disabled, don't include related ENV variables as part of the run
command in the runit service definition