Investigate use of memoization in TrialsHelper#trial_eligible_namespaces

Summary

Currently this method is memoized and I'm not sure it really does anything being memoized as the query is cached and rails doesn't execute it until something is called off of that relation. In those times, where the collection is executed upon, it is likely cached for the remainder of the request/response cycle or at least has no effect performance wise.

Solution

We should measure the query executions and see if this method needs to be memoized and if not, remove the memoization.