Fix deployer feature gate only for auto-deploy

What does this MR do?

With !4970 (merged) we introduced a feature gate on the gitlab_com:deployer task to make it a no-op if OMNIBUS_TRIGGERS_DEPLOYER is set to false.

This has the side effect of preventing deployments to other environments as well as preprod or releases.

This commit changes the feature gate to check AUTO_DEPLOY_OMNIBUS_TRIGGERS_DEPLOYER and only perform a no-op in case the package is an auto-deploy build.

Related issues

• Related to gitlab-com/gl-infra&201 (closed)
• Introduced by !4970 (merged)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• Pipeline is green on dev.gitlab.org if the change is touching anything besides documentation or internal cookbooks
• trigger-package has a green pipeline running against latest commit

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for the GitLab Chart opened