Improve and fix remote integration test suite

From https://github.com/microsoft/vscode/issues/147376 We found a few issues: - There are real differences between `test-remote-integration.sh` and `test-remote-integration.bat`. One of them is the amount of extensions being built. - In our CI, those extensions keep getting built all over again. First by the Electron integration tests, then by the Web integration tests, then by the Remote integration tests. It seems very wasteful. - ‼️ While it appears at first glace that the suite runs much faster on [Windows](https://dev.azure.com/monacotools/Monaco/_build/results?buildId=167146&view=logs&j=ca7250c6-0e2d-5a52-28a2-5c6aea023c92&t=3a10f1bd-e0fa-5fd5-e2f6-09648e53e7d4) than [macOS](https://dev.azure.com/monacotools/Monaco/_build/results?buildId=167146&view=logs&j=a5d99aad-4929-5289-bf4a-26b78032353d&t=d4649a83-a250-559c-eec3-8ca47a8ced50), you quickly realise that the tests are actually failing but the build reports them as having passed. On Windows, they fail quite early and a bunch of test suites never even run. On macOS, scroll to the end and you'll also see that they fail.