fix: GridMetrics including totals rows in visible rows when scrolled to bottom

[mattrunyon]

Noticed this while working on databars. The totals rows are being included in metrics.visibleRows when scrolled to the bottom. They were also being duplicated in allRows.

1. Create a table such as t = empty_table(1000).update(["X=ii"])
2. Add an aggregation
3. Scroll to bottom of the table
4. Log visibleRows or allRows from GridMetrics

Without this change you'll see that the totals row(s) (index 1000+) are included in those arrays when scrolled to the bottom. They are doubled in allRows

This doesn't seem to be the issue when aggregations are set to the top and the table is scrolled to the top.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.65%. Comparing base (0b37477) to head (5fb5000).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2194   +/-   ##
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  Coverage   46.64%   46.65%           
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  Files         692      692           
  Lines       38581    38583    +2     
  Branches     9820     9845   +25     
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+ Hits        17998    18000    +2     
  Misses      20530    20530           
  Partials       53       53           

Flag	Coverage Δ
unit	46.65% <100.00%> (+<0.01%)	⬆️

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