JIT: Treat unconditional store as the else case in if-conversion

[BoyBaykiller]

If-conversion phase now produces the same IR for these two cases:

void First(int tMinLeft, int tMinRight)
{
    bool leftCloser = false;
    if (tMinLeft < tMinRight)
    {
        leftCloser = true;
    }
}

void Second(int tMinLeft, int tMinRight)
{
    bool leftCloser;
    if (tMinLeft < tMinRight)
    {
        leftCloser = true;
    }
    else
    {
        leftCloser = false;
    }
}

The last unconditional store (leftCloser = false) is substituted into the SELECT which enables further optimization. Specifically it fixes #124713. Still need to investigate regressions.

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[BoyBaykiller]

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