users should remove former Go installation folder

What does this MR do?

It ensure users installing or updating from source will remove their former Go installation folder in /usr/local/go, to avoid raising errors that could lead to new issues being created.

Are there points in the code the reviewer needs to double check?

1. The rm -rf should not be verbose if folder does not exists.
2. May a user have some kind of configuration files in this folder ?

Why was this MR needed?

I did faced the error, that led me to the solution stated here : gitlab-workhorse#29 (comment 4155517)

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

gitlab-workhorse#29 (closed)