Update Roslyn to 5.3.0-2.25571.4

[RikkiGibson]

Insert dotnet/roslyn#81326

[RikkiGibson]

Unsure whether this failure is related to the change: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1210082&view=logs&jobId=a3295929-200b-59aa-e393-fb75e41fbb9b&j=a3295929-200b-59aa-e393-fb75e41fbb9b&t=0ff82b5c-074b-5da9-4da7-8c905468d821

FAIL test/omnisharp/omnisharpUnitTests/packages/zipInstaller.test.ts
  ● ZipInstaller › The folder is unzipped and the binaries have the expected permissions(except on Windows)

    expect(received).toBe(expected) // Object.is equality

    Expected: true
    Received: false

      60 |             await InstallZip(testZip.buffer, fileDescription, installationPath, absoluteBinaries, eventStream);
      61 |             for (const binaryPath of absoluteBinaries) {
    > 62 |                 expect(await util.fileExists(binaryPath.value)).toBe(true);
         |                                                                 ^
      63 |                 const mode = (await fs.stat(binaryPath.value)).mode;
      64 |                 expect(mode & 0o7777).toEqual(0o755);
      65 |             }

      at Object.<anonymous> (packages/zipInstaller.test.ts:62:65)

[dibarbet]

it is unrelated