Parallel tests are not working when CollectionAtribute is used.

[chrisdreams13]

Describe the bug
Parallel tests are not working when CollectionAtribute is used.

To Reproduce
Adding CollectionAttribute to example code.

namespace Xunit.DependencyInjection.Test.Parallelization;

[CollectionDefinition(nameof(Collection), DisableParallelization = false)]
public class Collection;

[Collection(nameof(Collection))]
public class ParallelTheoryTests(ConcurrencyFixture fixture) : IClassFixture<ConcurrencyFixture>
{
    [Theory]
    [InlineData(1)]
    [InlineData(2)]
    public async Task Theory(int _) => Assert.Equal(2, await fixture.CheckConcurrencyAsync());
}

Expected behavior
Parallel test should run with and without CollectionAttribute.

Desktop:

• OS: Win10
• Net: 8.0.0
• Xunit.DependencyInjection: 9.1.0

[pengweiqhca]

If [Collection], [CollectionDefinition(DisableParallelization = true)], [DisableParallelization] declared on the test class, the test class will run sequentially.

I will change the behavior if ParallelizationMode is Force

[pengweiqhca]

9.2.0

[chrisdreams13]

Works so well, thanks a lot.