Flaky test: ChangedImportAffectsExport

[Mikaël Mayer]

Seen here: https://github.com/dafny-lang/dafny/actions/runs/9892497446/job/27326613506?pr=5613

Waited for 49 seconds for new notification.
      Last received notification was SymbolStatus, Uri: file:///Users/runner/work/dafny/dafny/dafny/Source/DafnyLanguageServer.Test/bin/Debug/net6.0/cnxjtklj.ifb/importer.dfy, Version: 2, NamedVerifiables: NamedVerifiableStatus { NameRange = [start: (2, 8), end: (2, 9)], Status = Stale }, NamedVerifiableStatus { NameRange = [start: (3, 8), end: (3, 9)], Status = Stale }, NamedVerifiableStatus { NameRange = [start: (5, 9), end: (5, 12)], Status = Stale }
[xUnit.net 00:04:36.97]     Microsoft.Dafny.LanguageServer.IntegrationTest.Synchronization.CachingTest.ChangedImportAffectsExport [FAIL]