Do not escape URI when extracting path

## What does this MR do?

- remove escaping of URI parameters after they have already been unescaped in `ExtractsPath`
- remove spec that is relying on that behavior

## Why was this MR needed?

- spaces in directory names were escaped leading to 404 errors on repository files page

## What are the relevant issue numbers?

fixes gitlab-com/support-forum#952, #21106

See merge request !5878