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[RussKie]

Issue description

As per dotnet/wpf#6973 (comment), we need to invert these conditions (dotnet/sdk#27486) as we missed a version in the past:

    "csharp9orOlder": {
      "type": "generated",
      "generator": "regexMatch",
      "datatype": "bool",
      "parameters": {
        "pattern": "^(ISO-1|ISO-2|[1-7]|[8-9]|[8-9]\\.0|7\\.[0-3])$",
        "source": "langVersion"
      }
    },
    "csharp8orOlder": {
      "type": "generated",
      "generator": "regexMatch",
      "datatype": "bool",
      "parameters": {
        "pattern": "^(ISO-1|ISO-2|[1-7]|8|8\\.0|7\\.[0-3])$",
        "source": "langVersion"
      }
    },
    "csharp7orOlder": {
      "type": "generated",
      "generator": "regexMatch",
      "datatype": "bool",
      "parameters": {
        "pattern": "^(ISO-1|ISO-2|[1-7]|7\\.[0-3])$",
        "source": "langVersion"
      }
    },