Remove extra white-spaces [ci skip]

Follow up to 024e5e31
Use nested_scope? not shallow? to determine whether to copy options

The method `shallow?` returns false if the parent resource is a singleton so
we need to check if we're not inside a nested scope before copying the :path
and :as options to their shallow equivalents.

Fixes #14388.
Avoid concurrent test collision on the same memcache server by namespacing keys
Add an explicit require for 4ece124396669d3580e7f229ab407a0d4882727a rather than assume SecureRandom is available
Fix assertions
Drop custom tables after each test.

This is a step to prevent side effects when running tests. This will allow us to run them in random order.
WIP: Create DdlHelpers to ensure tables are dropped.