In RestrictedProcess class run process with Untrusted integrity (instead of Low)

[NikolayIT]

The following code is causing child process to crash. The reason is using SECURITY_MANDATORY_UNTRUSTED_RID

// Create the low integrity SID.
IntPtr integritySid;
if (!NativeMethods.AllocateAndInitializeSid(
        ref NativeMethods.SECURITY_MANDATORY_LABEL_AUTHORITY,
        1,
        NativeMethods.SECURITY_MANDATORY_UNTRUSTED_RID,
        0,
        0,
        0,
        0,
        0,
        0,
        0,
        out integritySid))
{
    throw new Win32Exception();
}