Don't cache test results while we are trying to track down flakeyness.

BuildAndTest.proj

@@ -11,6 +11,7 @@
     <SamplesSolution>$(MSBuildThisFileDirectory)src\Samples\Samples.sln</SamplesSolution>
     <Configuration Condition="'$(Configuration)' == ''">Debug</Configuration>
     <RunTestArgs Condition="'$(ManualTest)' == ''">$(RunTestArgs) -xml</RunTestArgs>
+    <RunTestArgs>$(RunTestArgs) -nocache</RunTestArgs>
     <RunTestArgs Condition="'$(Test64)' == 'true'">$(RunTestArgs) -test64</RunTestArgs>
     <RunTestArgs Condition="'$(TestVsi)' == 'true'">$(RunTestArgs) -testVsi</RunTestArgs>
     <RunTestArgs Condition="'$(Trait)' != ''">$(RunTestArgs) -trait:$(Trait)</RunTestArgs>