Fix bugs in the redux tests.

#### What's this PR do?
- Trimes trailing spaces in the ds script
- Fixes deadloop during screenshot capturing
- Adds UK example to test help documentation
- Brings back randomuser.js include required by UK tests

#### What are the relevant tickets?
- UK-specific integration tests integration: #3093 
- Test redux #3096 

I feel like the `Run UK-specific tests` line might be confusing here, since the other examples all show typeable input.