Fix assertion failures in assert_tpch_result_equal due to float sort ambiguity

[Matt711]

Description

When comparing results, sorting by non-float columns alone can leave rows with equal non-float keys in an arbitrary order, causing assert_frame_equal to fail on valid results. This PR retries the comparison using float columns as a secondary sort key before raising a validation error.

• Closes [BUG] Validate TPC-DS Q64 #22129

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[TomAugspurger]

So my original thinking here was that sorting on the float columns should be unnecessary. Suppose you have a sequence of (key, value) pairs, sorted by key:

Key, Value
0, x
0, x-e
0, x+e

Assuming e (or more precisely, 2e) is negligible, then any permutation of those rows should be considered equal to any other. And so my hope was that we could sort by Key and then validate with

1. assert_frame_equal on Key without any abs_tol
2. assert_frame_equal on all the columns with abs_tol

we'd correctly implement that logic. It would pass as long as abs_tol >= 2e, and fail otherwise (on the second stage).