Add installation type to usage ping data

What does this MR do?

Related to omnibus-gitlab#2418 (closed)

Add type of installation an attribute in usage pings. Just like figuring out version from VERSION file, this uses a TYPE file (we can find a better name). By default, its value is set to source, pointing that it is a source installation. In omnibus packages it is set to omnibus, in docker image it is set to docker and in our AWS AMI, we set it to aws. This is done by omnibus-gitlab!2561 (merged). Another MR will be submitted to version.gitlab.com codebase to accept this parameter. https://gitlab.com/gitlab-com/version-gitlab-com/merge_requests/145 adds the necessary stuff to version.gitlab.com

Why was this MR needed?

To get statistics on usage of our different installation methods. omnibus-gitlab#2418 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

omnibus-gitlab#2418 (closed)