Introduce a config to tune between linear and binary search for segmented aggregation

[zacw7]

#17886 introduced segmented aggregation. In the current implementation, it uses linear search to look for the start row of the last segment in each page. We tried binary search which was implemented as follows:

private int findLastSegmentStart(PagesHashStrategy pagesHashStrategy, Page page)
{
    int left = 0;
    int right = page.getPositionCount() - 1;
    while (left < right) {
        int middle = left + (right - left) / 2;
        if (pagesHashStrategy.rowEqualsRow(page.getPositionCount() - 1, page, middle, page)) {
            // Same segment - The last segment starts somewhere in [lo, mid]
            right = middle;
        }
        else {
            // Different segment - The last segment starts somewhere in (mid ~ hi]
            left = middle + 1;
        }
    }
    return right;
}

As no significant improvement was observed based on our testing, we switched it back to linear search given that the code would be more readable and concise.

However, ideally we'd like to keep both implementations and introduce a config to let the user decide to use which approach.