Disable crossroot_determinism for GCStress runs (#50706)

Author: AaronRobinsonMSFT

src/tests/readytorun/coreroot_determinism/coreroot_determinism.csproj

@@ -4,6 +4,9 @@
     <CLRTestKind>BuildAndRun</CLRTestKind>
     <CLRTestPriority>0</CLRTestPriority>
     <CLRTestTargetUnsupported Condition="'$(RuntimeFlavor)' != 'coreclr'">true</CLRTestTargetUnsupported>
+    <!-- See https://github.com/dotnet/runtime/issues/50704 -->
+    <GCStressIncompatible>true</GCStressIncompatible>
+    <!-- This is an explicit crossgen test -->
     <CrossGenTest>false</CrossGenTest>
     <OldToolsVersion>2.0</OldToolsVersion>
   </PropertyGroup>