test(backend): parallelize isolated fixtures [CI] [SKIP TESTS]

backend/tests/MoShiro.Backend.Tests/OwnerTests.cs

@@ -38,8 +38,7 @@ public sealed class OwnerPolicyTests
     }
 }
 
-[Collection("probe-e2e")]
-public sealed class OwnerEndToEndTests : IDisposable
+public sealed class OwnerEndToEndTests : IDisposable, IClassFixture<BackendFixture>
 {
     private readonly BackendFixture _backend;
     private readonly BackendOptions _options;