Make sure that we use IgnoreCommas for elastic/go-ucfg in all code paths

[rdner]

In all Go-based products we are using this library to parse configuration https://github.com/elastic/go-ucfg/

This library is trying to be smart about the values it finds in YAML. For example, a comma separated string gets parsed as an array, which is causing issues with password values.

We get complaints from customers, for example https://discuss.elastic.co/t/es-password-containing-comma-cant-be-passed-as-environment-variable/294450

This issue has been also reported in the library repository before, see elastic/go-ucfg#196

and it was fixed by adding the new
IgnoreCommas configuration option in this PR elastic/go-ucfg#197

It was also fixed in Elastic Agent with this PR #4436 but might not cover all the places where Elastic Agent parses configuration.

This fix was shipped with 8.14.0, see the changelog https://www.elastic.co/guide/en/fleet/8.14/release-notes-8.14.0.html

We need to make sure that all code paths in Elastic Agent and in other products are using this new configuration option.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)