Issue 817: MQ: Review use of functional tests; convert some to unit tests
(OData)

Found out that QueryComposition tests take up most of the time in OData
assembly. Most of these are redundant. Among the non-redundant ones, many
of them can have more targeted tests which I moved. The only tests that
are left in QueryCompositionTests.cs are testing that end-end querying
works with some basic scenarios.