Grammar correction (project-wide): "set up" and "setup" are different (in text, not code)

What does this MR do?

This MR corrects the grammar of "set up" and "setup" across the entire project: documentation, code comments, views, etc. It does not touch any actual code (I hope), except for strings that are visible to users. Setup and set up are used inconsistently throughout the project, sometimes correctly and sometimes not. I probably missed a few, but I think this corrects the vast majority of them. cc @rymai @axil @marcia

Ported to EE in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7329 (Merge EE First)

My only problem is that I'm not sure why the static analysis fails on the gitlab.pot (internationalisation) file. A few descriptions of runners (the ones in the examples below, actually) had this small mistake, so I corrected the views, the specs and the gitlab.pot files, which the test noticed, but I can't figure out what I need to do to have it pass. Any ideas?

Grammar Explanation

Setup is a noun or adjective, while set up is a verb. An easy way to think about it is to replace them with configuration or configure, so:
setup ≅ configuration (noun/adjective)
set up ≅ configure (verb)

Examples from GitLab itself (with images below, red boxes = incorrect, green boxes = correct):

You can setup as many Runners as you need. ≅ You can configuration as many Runners as you need.❌
You can set up as many Runners as you need. ≅ You can configure as many Runners as you need.⭕

Specify the following URL during the Runner setup: ≅ Specify the following URL during the Runner configuration:⭕
Specify the following URL during the Runner set up: ≅ Specify the following URL during the Runner configure:❌

Does this MR meet the acceptance criteria?

• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guidesent/README.html#databases-guides)