Fix skip condition for java tests (#60240)

Author: wtgodbe

src/SignalR/clients/java/signalr/test/signalr.client.java.Tests.javaproj

@@ -7,7 +7,7 @@
     <SkipHelixArm>true</SkipHelixArm>
     <SkipHelixAlpine>true</SkipHelixAlpine>
     <!-- Temporary while Mac machines get new JDK -->
-    <SkipHelixQueues>OSX.13.Amd64.Open;$(SkipHelixQueues)</SkipHelixQueues>
+    <SkipHelixQueues>OSX.15.Amd64.Open;$(SkipHelixQueues)</SkipHelixQueues>
     <PublishDir>$(OutputPath)</PublishDir>
     <TestDependsOnJava>true</TestDependsOnJava>
   </PropertyGroup>