fix(python): Add height check to frame-level row indexing when key is int

[mcrumiller]

Closes #20775.

The issue is that df.slice(idx, 1) was being called for a single integer index key, and slices return the empty set instead of raising when idx is out of bounds. This PR adds a small height check.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.77%. Comparing base (6753bb6) to head (588d19a).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20778      +/-   ##
==========================================
+ Coverage   79.74%   79.77%   +0.03%     
==========================================
  Files        1561     1561              
  Lines      222012   221925      -87     
  Branches     2530     2531       +1     
==========================================
+ Hits       177043   177044       +1     
+ Misses      44387    44299      -88     
  Partials      582      582              

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[mcrumiller]

Need to check negative indexing as well.