TrueZip64 tests take a significant amount of time to run locally and run by default

I occasionally run `libs.test` subset (or Copilot decides to do it for me) and some of these ZIP64 tests take a significant amount of time to run on a MacBook Neo. ``` ystem.IO.Compression.ZipFile.Tests: [Long Running Test] 'System.IO.Compression.Tests.ZipFile_EncryptionTests.Encryption_TrueZip64_LargeEntry_RoundTrip', Elapsed: 00:04:08 System.IO.Compression.ZipFile.Tests: [Long Running Test] 'System.IO.Compression.Tests.ZipFile_EncryptionTests.Encryption_TrueZip64_LargeEntry_RoundTrip', Elapsed: 00:06:08 System.IO.Compression.ZipFile.Tests: [Long Running Test] 'System.IO.Compression.Tests.ZipFile_EncryptionTests.Encryption_TrueZip64_LargeEntry_RoundTrip', Elapsed: 00:08:08 System.IO.Compression.ZipFile.Tests: [Long Running Test] 'System.IO.Compression.Tests.ZipFile_EncryptionTests.Encryption_TrueZip64_LargeEntry_RoundTrip', Elapsed: 00:10:08 System.IO.Compression.ZipFile.Tests: [Long Running Test] 'System.IO.Compression.Tests.ZipFile_EncryptionTests.Encryption_TrueZip64_LargeEntry_UpdateMode_Throws', Elapsed: 00:02:04 System.IO.Compression.ZipFile.Tests: [Long Running Test] 'System.IO.Compression.Tests.ZipFile_EncryptionTests.Encryption_TrueZip64_LargeEntry_UpdateMode_Throws', Elapsed: 00:04:04 ``` These tests are already marked `SkipCI` - perhaps we should consider marking them outer loop. I do not think contributors that want to work in System.IO.Compression want a test suite that takes 15 minutes to complete.