Make it easier to call Gitlab::Tracking.event with standard context

The following discussion from !49873 (merged) should be addressed:

• @ali-gitlab started a discussion: (+1 comment)

  standard_context: ::Gitlab::Tracking::StandardContext.new(namespace: @parent_group, project: issue.project)

  I wonder how we could make this more user-friendly (i.e. easier for the caller) 🤔

See !49873 (comment 485723921) for suggestions.

/cc @gitlab-org/growth/product-intelligence/engineers