Remove the /sandboxes page, and references from /demo page
This was raised by @MikeyMJCO in the infrastructure channel:
- https://civicrm.org/demo : has a paragraph at the bottom talking about development sandboxes, but the demos run dmaster anyway, so it's a bit redundant.
- https://civicrm.org/sandboxes : has a lot of deprecated information (ex: 4.4 and 4.6 demos, most of which are turned off).
- On /demo, remove the "development sandboxes" section
- On /demo, rename "Additional Demos & Testing Sandboxes" to "Additional Demos"
- Unpublish the /sandboxes page
- Redirect /sandboxes to /demo