RuboCop: Fix prefix configuration for RSpec/ContextWording

What does this MR do and why?

In YAML, we must quote some string literals like no and on otherwise they evaluate to false and true.

This removes a bunch of offenses because we do allow:

  context 'on homepage' do
    ...
  end

Follow-up of !92980 (merged).

Screenshots or screen recordings

Configuration via: rubocop --show-cops | rg --multiline --multiline-dotall "RSpec/ContextWording:.*?\n$\n"

Before

RSpec/ContextWording:
  Description: Checks that `context` docstring starts with an allowed prefix.
  Enabled: true
  Prefixes:
  - when
  - with
  - without
  - for
  - and
  - true
  - in
  - as
  - if
  VersionAdded: '1.20'
  VersionChanged: 1.20.1
  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/ContextWording

After

RSpec/ContextWording:
  Description: Checks that `context` docstring starts with an allowed prefix.
  Enabled: true
  Prefixes:
  - when
  - with
  - without
  - for
  - and
  - 'on'
  - in
  - as
  - if
  VersionAdded: '1.20'
  VersionChanged: 1.20.1
  StyleGuide: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/ContextWording

Diff

--- before	2022-08-03 22:22:11.065403211 +0200
+++ after	2022-08-03 22:22:05.361487381 +0200
@@ -7,7 +7,7 @@
   - without
   - for
   - and
-  - true
+  - 'on'
   - in
   - as
   - if

How to set up and validate locally

bin/rake rubocop:todo:generate[RSpec/ContextWording]

MR acceptance checklist

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