Re-DEBUG factory tests that are inconsistent

These need changes in assumptions to match current behaviors. We don't account for what the instant debug abort should do.

StackExchange.Redis.Tests/ExceptionFactoryTests.cs

 using System;
+using System.Diagnostics;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -28,6 +29,7 @@ public void NullSnapshot()
         }
 
         [Fact]
+        [Conditional("DEBUG")]
         public void MultipleEndpointsThrowConnectionException()
         {
             try
@@ -76,6 +78,7 @@ public void NullInnerExceptionForMultipleEndpointsWithNoLastException()
         }
 
         [Fact]
+        [Conditional("DEBUG")]
         public void ServerTakesPrecendenceOverSnapshot()
         {
             try