Exclude MAUI playground from build (for now)

Author: jfversluis

eng/Build.props

@@ -15,7 +15,9 @@
     <ProjectToBuild Include="$(RepoRoot)eng\dcppack\**\*.csproj" />
     <ProjectToBuild Include="$(RepoRoot)eng\dashboardpack\**\*.csproj" />
 
-    <ProjectToBuild Include="$(RepoRoot)playground\**\*.csproj" />
+    <!-- Exclude AspireWithMaui playground as it requires the .NET MAUI workload.
+         The playground can still be built directly when needed. -->
+    <ProjectToBuild Include="$(RepoRoot)playground\**\*.csproj" Exclude="$(RepoRoot)playground\AspireWithMaui\**\*.csproj" />
 
     <!-- `$(SkipTestProjects)` allows skipping test projects from being
           included in the build at all. This is useful for cases like when we are