[browser][tests] Activate System.Private.Uri.Functional.Tests (#39817)

Local:

```
info: test[0]
        Tests run: 883, Errors: 0, Failures: 0, Skipped: 1. Time: 188.7140968s
```

Author: kjpou1

src/libraries/tests.proj

@@ -32,7 +32,6 @@
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Linq.Parallel\tests\System.Linq.Parallel.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.Http\tests\FunctionalTests\System.Net.Http.Functional.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.WebSockets.Client\tests\System.Net.WebSockets.Client.Tests.csproj" />
-    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Private.Uri\tests\FunctionalTests\System.Private.Uri.Functional.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.ValueTuple\tests\System.ValueTuple.Tests.csproj" />
   </ItemGroup>